Revision tags: v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14, v6.6.13, v6.6.12, v6.6.11, v6.6.10, v6.6.9, v6.6.8, v6.6.7, v6.6.6, v6.6.5, v6.6.4, v6.6.3, v6.6.2, v6.5.11, v6.6.1, v6.5.10, v6.6, v6.5.9, v6.5.8, v6.5.7, v6.5.6, v6.5.5, v6.5.4, v6.5.3, v6.5.2, v6.1.51, v6.5.1, v6.1.50, v6.5, v6.1.49, v6.1.48, v6.1.46, v6.1.45, v6.1.44, v6.1.43, v6.1.42, v6.1.41, v6.1.40, v6.1.39, v6.1.38, v6.1.37, v6.1.36, v6.4, v6.1.35, v6.1.34, v6.1.33, v6.1.32, v6.1.31, v6.1.30, v6.1.29, v6.1.28, v6.1.27, v6.1.26, v6.3, v6.1.25, v6.1.24, v6.1.23, v6.1.22, v6.1.21, v6.1.20, v6.1.19, v6.1.18, v6.1.17, v6.1.16, v6.1.15, v6.1.14, v6.1.13, v6.2, v6.1.12, v6.1.11, v6.1.10, v6.1.9, v6.1.8, v6.1.7, v6.1.6, v6.1.5, v6.0.19, v6.0.18, v6.1.4, v6.1.3, v6.0.17, v6.1.2, v6.0.16, v6.1.1, v6.0.15, v6.0.14, v6.0.13, v6.1, v6.0.12, v6.0.11, v6.0.10, v5.15.80, v6.0.9, v5.15.79, v6.0.8, v5.15.78, v6.0.7, v5.15.77 |
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#
e7bb66f7 |
| 02-Nov-2022 |
Jianlin Lv <iecedge@gmail.com> |
tracepoint: Allow livepatch module add trace event
In the case of keeping the system running, the preferred method for tracing the kernel is dynamic tracing (kprobe), but the drawback of this method
tracepoint: Allow livepatch module add trace event
In the case of keeping the system running, the preferred method for tracing the kernel is dynamic tracing (kprobe), but the drawback of this method is that events are lost, especially when tracing packages in the network stack.
Livepatching provides a potential solution, which is to reimplement the function you want to replace and insert a static tracepoint. In such a way, custom stable static tracepoints can be expanded without rebooting the system.
Link: https://lkml.kernel.org/r/20221102160236.11696-1-iecedge@gmail.com
Signed-off-by: Jianlin Lv <iecedge@gmail.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Revision tags: v5.15.76, v6.0.6, v6.0.5, v5.15.75, v6.0.4, v6.0.3, v6.0.2, v5.15.74, v5.15.73, v6.0.1, v5.15.72, v6.0, v5.15.71, v5.15.70, v5.15.69, v5.15.68 |
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#
51714678 |
| 14-Sep-2022 |
Zhen Lei <thunder.leizhen@huawei.com> |
tracepoint: Optimize the critical region of mutex_lock in tracepoint_module_coming()
The memory allocation of 'tp_mod' does not require mutex_lock() protection, move it out.
Link: https://lkml.kern
tracepoint: Optimize the critical region of mutex_lock in tracepoint_module_coming()
The memory allocation of 'tp_mod' does not require mutex_lock() protection, move it out.
Link: https://lkml.kernel.org/r/20220914061416.1630-1-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Revision tags: v5.15.67, v5.15.66, v5.15.65, v5.15.64 |
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#
54be5509 |
| 29-Aug-2022 |
Alison Schofield <alison.schofield@intel.com> |
tracepoint: Allow trace events in modules with TAINT_TEST
Commit 2852ca7fba9f ("panic: Taint kernel if tests are run") introduced a new taint type, TAINT_TEST, to signal that an in-kernel test modul
tracepoint: Allow trace events in modules with TAINT_TEST
Commit 2852ca7fba9f ("panic: Taint kernel if tests are run") introduced a new taint type, TAINT_TEST, to signal that an in-kernel test module has been loaded.
TAINT_TEST taint type defaults into a 'bad_taint' list for kernel tracing and blocks the creation of trace events. This causes a problem for CXL testing where loading the cxl_test module makes all CXL modules out-of-tree, blocking any trace events.
Trace events are in development for CXL at the moment and this issue was found in test with v6.0-rc1.
Link: https://lkml.kernel.org/r/20220829171048.263065-1-alison.schofield@intel.com
Fixes: 2852ca7fba9f7 ("panic: Taint kernel if tests are run") Reported-by: Ira Weiny <ira.weiny@intel.com> Suggested-by: Dan Williams <dan.j.williams@intel.com> Tested-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: David Gow <davidgow@google.com> Signed-off-by: Alison Schofield <alison.schofield@intel.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Revision tags: v5.15.63, v5.15.62, v5.15.61, v5.15.60, v5.15.59, v5.19, v5.15.58, v5.15.57, v5.15.56, v5.15.55, v5.15.54, v5.15.53, v5.15.52, v5.15.51, v5.15.50, v5.15.49, v5.15.48, v5.15.47, v5.15.46, v5.15.45, v5.15.44, v5.15.43, v5.15.42, v5.18, v5.15.41, v5.15.40, v5.15.39, v5.15.38, v5.15.37, v5.15.36, v5.15.35, v5.15.34, v5.15.33, v5.15.32, v5.15.31, v5.17, v5.15.30, v5.15.29, v5.15.28, v5.15.27, v5.15.26, v5.15.25, v5.15.24, v5.15.23, v5.15.22, v5.15.21, v5.15.20, v5.15.19, v5.15.18, v5.15.17, v5.4.173, v5.15.16, v5.15.15, v5.16, v5.15.10, v5.15.9, v5.15.8, v5.15.7, v5.15.6, v5.15.5, v5.15.4, v5.15.3, v5.15.2, v5.15.1, v5.15, v5.14.14, v5.14.13, v5.14.12, v5.14.11, v5.14.10, v5.14.9, v5.14.8, v5.14.7, v5.14.6, v5.10.67, v5.10.66, v5.14.5, v5.14.4, v5.10.65, v5.14.3, v5.10.64, v5.14.2, v5.10.63, v5.14.1, v5.10.62, v5.14, v5.10.61, v5.10.60 |
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#
bd740953 |
| 16-Aug-2021 |
zhaoxiao <zhaoxiao@uniontech.com> |
tracepoint: Fix kerneldoc comments
Fix function name in tracepoint.c kernel-doc comment to remove a warning found by clang_w1.
kernel/tracepoint.c:589: warning: expecting prototype for register_tra
tracepoint: Fix kerneldoc comments
Fix function name in tracepoint.c kernel-doc comment to remove a warning found by clang_w1.
kernel/tracepoint.c:589: warning: expecting prototype for register_tracepoint_notifier(). Prototype was for register_tracepoint_module_notifier() instead kernel/tracepoint.c:613: warning: expecting prototype for unregister_tracepoint_notifier(). Prototype was for unregister_tracepoint_module_notifier() instead
Link: https://lkml.kernel.org/r/20210816052430.16539-1-zhaoxiao@uniontech.com
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: zhaoxiao <zhaoxiao@uniontech.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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#
7b40066c |
| 05-Aug-2021 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
tracepoint: Use rcu get state and cond sync for static call updates
State transitions from 1->0->1 and N->2->1 callbacks require RCU synchronization. Rather than performing the RCU synchronization e
tracepoint: Use rcu get state and cond sync for static call updates
State transitions from 1->0->1 and N->2->1 callbacks require RCU synchronization. Rather than performing the RCU synchronization every time the state change occurs, which is quite slow when many tracepoints are registered in batch, instead keep a snapshot of the RCU state on the most recent transitions which belong to a chain, and conditionally wait for a grace period on the last transition of the chain if one g.p. has not elapsed since the last snapshot.
This applies to both RCU and SRCU.
This brings the performance regression caused by commit 231264d6927f ("Fix: tracepoint: static call function vs data state mismatch") back to what it was originally.
Before this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m10.593s user 0m0.017s sys 0m0.259s
After this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m0.878s user 0m0.000s sys 0m0.103s
Link: https://lkml.kernel.org/r/20210805192954.30688-1-mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Stefan Metzmacher <metze@samba.org> Fixes: 231264d6927f ("Fix: tracepoint: static call function vs data state mismatch") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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#
231264d6 |
| 05-Aug-2021 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
tracepoint: Fix static call function vs data state mismatch
On a 1->0->1 callbacks transition, there is an issue with the new callback using the old callback's data.
Considering __DO_TRACE_CALL:
tracepoint: Fix static call function vs data state mismatch
On a 1->0->1 callbacks transition, there is an issue with the new callback using the old callback's data.
Considering __DO_TRACE_CALL:
do { \ struct tracepoint_func *it_func_ptr; \ void *__data; \ it_func_ptr = \ rcu_dereference_raw((&__tracepoint_##name)->funcs); \ if (it_func_ptr) { \ __data = (it_func_ptr)->data; \
----> [ delayed here on one CPU (e.g. vcpu preempted by the host) ]
static_call(tp_func_##name)(__data, args); \ } \ } while (0)
It has loaded the tp->funcs of the old callback, so it will try to use the old data. This can be fixed by adding a RCU sync anywhere in the 1->0->1 transition chain.
On a N->2->1 transition, we need an rcu-sync because you may have a sequence of 3->2->1 (or 1->2->1) where the element 0 data is unchanged between 2->1, but was changed from 3->2 (or from 1->2), which may be observed by the static call. This can be fixed by adding an unconditional RCU sync in transition 2->1.
Note, this fixes a correctness issue at the cost of adding a tremendous performance regression to the disabling of tracepoints.
Before this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m0.778s user 0m0.000s sys 0m0.061s
After this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m10.593s user 0m0.017s sys 0m0.259s
A follow up fix will introduce a more lightweight scheme based on RCU get_state and cond_sync, that will return the performance back to what it was. As both this change and the lightweight versions are complex on their own, for bisecting any issues that this may cause, they are kept as two separate changes.
Link: https://lkml.kernel.org/r/20210805132717.23813-3-mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Stefan Metzmacher <metze@samba.org> Fixes: d25e37d89dd2 ("tracepoint: Optimize using static_call()") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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#
f7ec4121 |
| 05-Aug-2021 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
tracepoint: static call: Compare data on transition from 2->1 callees
On transition from 2->1 callees, we should be comparing .data rather than .func, because the same callback can be registered twi
tracepoint: static call: Compare data on transition from 2->1 callees
On transition from 2->1 callees, we should be comparing .data rather than .func, because the same callback can be registered twice with different data, and what we care about here is that the data of array element 0 is unchanged to skip rcu sync.
Link: https://lkml.kernel.org/r/20210805132717.23813-2-mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Stefan Metzmacher <metze@samba.org> Fixes: 547305a64632 ("tracepoint: Fix out of sync data passing by static caller") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Revision tags: v5.10.53 |
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#
352384d5 |
| 22-Jul-2021 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoints: Update static_call before tp_funcs when adding a tracepoint
Because of the significant overhead that retpolines pose on indirect calls, the tracepoint code was updated to use the new "s
tracepoints: Update static_call before tp_funcs when adding a tracepoint
Because of the significant overhead that retpolines pose on indirect calls, the tracepoint code was updated to use the new "static_calls" that can modify the running code to directly call a function instead of using an indirect caller, and this function can be changed at runtime.
In the tracepoint code that calls all the registered callbacks that are attached to a tracepoint, the following is done:
it_func_ptr = rcu_dereference_raw((&__tracepoint_##name)->funcs); if (it_func_ptr) { __data = (it_func_ptr)->data; static_call(tp_func_##name)(__data, args); }
If there's just a single callback, the static_call is updated to just call that callback directly. Once another handler is added, then the static caller is updated to call the iterator, that simply loops over all the funcs in the array and calls each of the callbacks like the old method using indirect calling.
The issue was discovered with a race between updating the funcs array and updating the static_call. The funcs array was updated first and then the static_call was updated. This is not an issue as long as the first element in the old array is the same as the first element in the new array. But that assumption is incorrect, because callbacks also have a priority field, and if there's a callback added that has a higher priority than the callback on the old array, then it will become the first callback in the new array. This means that it is possible to call the old callback with the new callback data element, which can cause a kernel panic.
static_call = callback1() funcs[] = {callback1,data1}; callback2 has higher priority than callback1
CPU 1 CPU 2 ----- -----
new_funcs = {callback2,data2}, {callback1,data1}
rcu_assign_pointer(tp->funcs, new_funcs);
/* * Now tp->funcs has the new array * but the static_call still calls callback1 */
it_func_ptr = tp->funcs [ new_funcs ] data = it_func_ptr->data [ data2 ] static_call(callback1, data);
/* Now callback1 is called with * callback2's data */
[ KERNEL PANIC ]
update_static_call(iterator);
To prevent this from happening, always switch the static_call to the iterator before assigning the tp->funcs to the new array. The iterator will always properly match the callback with its data.
To trigger this bug:
In one terminal:
while :; do hackbench 50; done
In another terminal
echo 1 > /sys/kernel/tracing/events/sched/sched_waking/enable while :; do echo 1 > /sys/kernel/tracing/set_event_pid; sleep 0.5 echo 0 > /sys/kernel/tracing/set_event_pid; sleep 0.5 done
And it doesn't take long to crash. This is because the set_event_pid adds a callback to the sched_waking tracepoint with a high priority, which will be called before the sched_waking trace event callback is called.
Note, the removal to a single callback updates the array first, before changing the static_call to single callback, which is the proper order as the first element in the array is the same as what the static_call is being changed to.
Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Fixes: d25e37d89dd2f ("tracepoint: Optimize using static_call()") Reported-by: Stefan Metzmacher <metze@samba.org> tested-by: Stefan Metzmacher <metze@samba.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Revision tags: v5.10.52, v5.10.51, v5.10.50, v5.10.49 |
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#
9913d574 |
| 29-Jun-2021 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
All internal use cases for tracepoint_probe_register() is set to not ever be called with the same function and data. If it is, i
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
All internal use cases for tracepoint_probe_register() is set to not ever be called with the same function and data. If it is, it is considered a bug, as that means the accounting of handling tracepoints is corrupted. If the function and data for a tracepoint is already registered when tracepoint_probe_register() is called, it will call WARN_ON_ONCE() and return with EEXISTS.
The BPF system call can end up calling tracepoint_probe_register() with the same data, which now means that this can trigger the warning because of a user space process. As WARN_ON_ONCE() should not be called because user space called a system call with bad data, there needs to be a way to register a tracepoint without triggering a warning.
Enter tracepoint_probe_register_may_exist(), which can be called, but will not cause a WARN_ON() if the probe already exists. It will still error out with EEXIST, which will then be sent to the user space that performed the BPF system call.
This keeps the previous testing for issues with other users of the tracepoint code, while letting BPF call it with duplicated data and not warn about it.
Link: https://lore.kernel.org/lkml/20210626135845.4080-1-penguin-kernel@I-love.SAKURA.ne.jp/ Link: https://syzkaller.appspot.com/bug?id=41f4318cf01762389f4d1c1c459da4f542fe5153
Cc: stable@vger.kernel.org Fixes: c4f6699dfcb85 ("bpf: introduce BPF_RAW_TRACEPOINT") Reported-by: syzbot <syzbot+721aa903751db87aa244@syzkaller.appspotmail.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: syzbot+721aa903751db87aa244@syzkaller.appspotmail.com Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Revision tags: v5.13, v5.10.46, v5.10.43, v5.10.42, v5.10.41, v5.10.40, v5.10.39, v5.4.119, v5.10.36, v5.10.35, v5.10.34, v5.4.116, v5.10.33, v5.12, v5.10.32, v5.10.31, v5.10.30, v5.10.27, v5.10.26, v5.10.25, v5.10.24, v5.10.23, v5.10.22, v5.10.21, v5.10.20, v5.10.19, v5.4.101, v5.10.18, v5.10.17, v5.11, v5.10.16, v5.10.15, v5.10.14 |
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#
7211f0a2 |
| 04-Feb-2021 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoints: Code clean up
Restructure the code a bit to make it simpler, fix some formatting problems and add READ_ONCE/WRITE_ONCE to make sure there's no compiler load/store tearing to the variabl
tracepoints: Code clean up
Restructure the code a bit to make it simpler, fix some formatting problems and add READ_ONCE/WRITE_ONCE to make sure there's no compiler load/store tearing to the variables that can be accessed across CPUs.
Started with Mathieu Desnoyers's patch:
Link: https://lore.kernel.org/lkml/20210203175741.20665-1-mathieu.desnoyers@efficios.com/
And will keep his signature, but I will take the responsibility of this being correct, and keep the authorship.
Link: https://lkml.kernel.org/r/20210204143004.61126582@gandalf.local.home
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Revision tags: v5.10 |
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#
befe6d94 |
| 18-Nov-2020 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoint: Do not fail unregistering a probe due to memory failure
The list of tracepoint callbacks is managed by an array that is protected by RCU. To update this array, a new array is allocated,
tracepoint: Do not fail unregistering a probe due to memory failure
The list of tracepoint callbacks is managed by an array that is protected by RCU. To update this array, a new array is allocated, the updates are copied over to the new array, and then the list of functions for the tracepoint is switched over to the new array. After a completion of an RCU grace period, the old array is freed.
This process happens for both adding a callback as well as removing one. But on removing a callback, if the new array fails to be allocated, the callback is not removed, and may be used after it is freed by the clients of the tracepoint.
There's really no reason to fail if the allocation for a new array fails when removing a function. Instead, the function can simply be replaced by a stub function that could be cleaned up on the next modification of the array. That is, instead of calling the function registered to the tracepoint, it would call a stub function in its place.
Link: https://lore.kernel.org/r/20201115055256.65625-1-mmullins@mmlx.us Link: https://lore.kernel.org/r/20201116175107.02db396d@gandalf.local.home Link: https://lore.kernel.org/r/20201117211836.54acaef2@oasis.local.home Link: https://lkml.kernel.org/r/20201118093405.7a6d2290@gandalf.local.home
[ Note, this version does use undefined compiler behavior (assuming that a stub function with no parameters or return, can be called by a location that thinks it has parameters but still no return value. Static calls do the same thing, so this trick is not without precedent.
There's another solution that uses RCU tricks and is more complex, but can be an alternative if this solution becomes an issue.
Link: https://lore.kernel.org/lkml/20210127170721.58bce7cc@gandalf.local.home/ ]
Cc: Peter Zijlstra <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Song Liu <songliubraving@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Andrii Nakryiko <andriin@fb.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@chromium.org> Cc: netdev <netdev@vger.kernel.org> Cc: bpf <bpf@vger.kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Florian Weimer <fw@deneb.enyo.de> Fixes: 97e1c18e8d17b ("tracing: Kernel Tracepoints") Reported-by: syzbot+83aa762ef23b6f0d1991@syzkaller.appspotmail.com Reported-by: syzbot+d29e58bb557324e55e5e@syzkaller.appspotmail.com Reported-by: Matt Mullins <mmullins@mmlx.us> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Tested-by: Matt Mullins <mmullins@mmlx.us>
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#
524666cb |
| 16-Nov-2020 |
Gabriel Krisman Bertazi <krisman@collabora.com> |
tracepoints: Migrate to use SYSCALL_WORK flag
On architectures using the generic syscall entry code the architecture independent syscall work is moved to flags in thread_info::syscall_work. This rem
tracepoints: Migrate to use SYSCALL_WORK flag
On architectures using the generic syscall entry code the architecture independent syscall work is moved to flags in thread_info::syscall_work. This removes architecture dependencies and frees up TIF bits.
Define SYSCALL_WORK_SYSCALL_TRACEPOINT, use it in the generic entry code and convert the code which uses the TIF specific helper functions to use the new *_syscall_work() helpers which either resolve to the new mode for users of the generic entry code or to the TIF based functions for the other architectures.
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Andy Lutomirski <luto@kernel.org> Link: https://lore.kernel.org/r/20201116174206.2639648-6-krisman@collabora.com
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#
9a4f1dc8 |
| 05-Aug-2021 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
tracepoint: Use rcu get state and cond sync for static call updates
commit 7b40066c97ec66a44e388f82fcf694987451768f upstream.
State transitions from 1->0->1 and N->2->1 callbacks require RCU synchr
tracepoint: Use rcu get state and cond sync for static call updates
commit 7b40066c97ec66a44e388f82fcf694987451768f upstream.
State transitions from 1->0->1 and N->2->1 callbacks require RCU synchronization. Rather than performing the RCU synchronization every time the state change occurs, which is quite slow when many tracepoints are registered in batch, instead keep a snapshot of the RCU state on the most recent transitions which belong to a chain, and conditionally wait for a grace period on the last transition of the chain if one g.p. has not elapsed since the last snapshot.
This applies to both RCU and SRCU.
This brings the performance regression caused by commit 231264d6927f ("Fix: tracepoint: static call function vs data state mismatch") back to what it was originally.
Before this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m10.593s user 0m0.017s sys 0m0.259s
After this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m0.878s user 0m0.000s sys 0m0.103s
Link: https://lkml.kernel.org/r/20210805192954.30688-1-mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Stefan Metzmacher <metze@samba.org> Fixes: 231264d6927f ("Fix: tracepoint: static call function vs data state mismatch") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
7799ad4d |
| 05-Aug-2021 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
tracepoint: Fix static call function vs data state mismatch
commit 231264d6927f6740af36855a622d0e240be9d94c upstream.
On a 1->0->1 callbacks transition, there is an issue with the new callback usin
tracepoint: Fix static call function vs data state mismatch
commit 231264d6927f6740af36855a622d0e240be9d94c upstream.
On a 1->0->1 callbacks transition, there is an issue with the new callback using the old callback's data.
Considering __DO_TRACE_CALL:
do { \ struct tracepoint_func *it_func_ptr; \ void *__data; \ it_func_ptr = \ rcu_dereference_raw((&__tracepoint_##name)->funcs); \ if (it_func_ptr) { \ __data = (it_func_ptr)->data; \
----> [ delayed here on one CPU (e.g. vcpu preempted by the host) ]
static_call(tp_func_##name)(__data, args); \ } \ } while (0)
It has loaded the tp->funcs of the old callback, so it will try to use the old data. This can be fixed by adding a RCU sync anywhere in the 1->0->1 transition chain.
On a N->2->1 transition, we need an rcu-sync because you may have a sequence of 3->2->1 (or 1->2->1) where the element 0 data is unchanged between 2->1, but was changed from 3->2 (or from 1->2), which may be observed by the static call. This can be fixed by adding an unconditional RCU sync in transition 2->1.
Note, this fixes a correctness issue at the cost of adding a tremendous performance regression to the disabling of tracepoints.
Before this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m0.778s user 0m0.000s sys 0m0.061s
After this commit:
# trace-cmd start -e all # time trace-cmd start -p nop
real 0m10.593s user 0m0.017s sys 0m0.259s
A follow up fix will introduce a more lightweight scheme based on RCU get_state and cond_sync, that will return the performance back to what it was. As both this change and the lightweight versions are complex on their own, for bisecting any issues that this may cause, they are kept as two separate changes.
Link: https://lkml.kernel.org/r/20210805132717.23813-3-mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Stefan Metzmacher <metze@samba.org> Fixes: d25e37d89dd2 ("tracepoint: Optimize using static_call()") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
14673e19 |
| 05-Aug-2021 |
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
tracepoint: static call: Compare data on transition from 2->1 callees
commit f7ec4121256393e1d03274acdca73eb18958f27e upstream.
On transition from 2->1 callees, we should be comparing .data rather
tracepoint: static call: Compare data on transition from 2->1 callees
commit f7ec4121256393e1d03274acdca73eb18958f27e upstream.
On transition from 2->1 callees, we should be comparing .data rather than .func, because the same callback can be registered twice with different data, and what we care about here is that the data of array element 0 is unchanged to skip rcu sync.
Link: https://lkml.kernel.org/r/20210805132717.23813-2-mathieu.desnoyers@efficios.com Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Stefan Metzmacher <metze@samba.org> Fixes: 547305a64632 ("tracepoint: Fix out of sync data passing by static caller") Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
0edad8b9 |
| 22-Jul-2021 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoints: Update static_call before tp_funcs when adding a tracepoint
commit 352384d5c84ebe40fa77098cc234fe173247d8ef upstream.
Because of the significant overhead that retpolines pose on indire
tracepoints: Update static_call before tp_funcs when adding a tracepoint
commit 352384d5c84ebe40fa77098cc234fe173247d8ef upstream.
Because of the significant overhead that retpolines pose on indirect calls, the tracepoint code was updated to use the new "static_calls" that can modify the running code to directly call a function instead of using an indirect caller, and this function can be changed at runtime.
In the tracepoint code that calls all the registered callbacks that are attached to a tracepoint, the following is done:
it_func_ptr = rcu_dereference_raw((&__tracepoint_##name)->funcs); if (it_func_ptr) { __data = (it_func_ptr)->data; static_call(tp_func_##name)(__data, args); }
If there's just a single callback, the static_call is updated to just call that callback directly. Once another handler is added, then the static caller is updated to call the iterator, that simply loops over all the funcs in the array and calls each of the callbacks like the old method using indirect calling.
The issue was discovered with a race between updating the funcs array and updating the static_call. The funcs array was updated first and then the static_call was updated. This is not an issue as long as the first element in the old array is the same as the first element in the new array. But that assumption is incorrect, because callbacks also have a priority field, and if there's a callback added that has a higher priority than the callback on the old array, then it will become the first callback in the new array. This means that it is possible to call the old callback with the new callback data element, which can cause a kernel panic.
static_call = callback1() funcs[] = {callback1,data1}; callback2 has higher priority than callback1
CPU 1 CPU 2 ----- -----
new_funcs = {callback2,data2}, {callback1,data1}
rcu_assign_pointer(tp->funcs, new_funcs);
/* * Now tp->funcs has the new array * but the static_call still calls callback1 */
it_func_ptr = tp->funcs [ new_funcs ] data = it_func_ptr->data [ data2 ] static_call(callback1, data);
/* Now callback1 is called with * callback2's data */
[ KERNEL PANIC ]
update_static_call(iterator);
To prevent this from happening, always switch the static_call to the iterator before assigning the tp->funcs to the new array. The iterator will always properly match the callback with its data.
To trigger this bug:
In one terminal:
while :; do hackbench 50; done
In another terminal
echo 1 > /sys/kernel/tracing/events/sched/sched_waking/enable while :; do echo 1 > /sys/kernel/tracing/set_event_pid; sleep 0.5 echo 0 > /sys/kernel/tracing/set_event_pid; sleep 0.5 done
And it doesn't take long to crash. This is because the set_event_pid adds a callback to the sched_waking tracepoint with a high priority, which will be called before the sched_waking trace event callback is called.
Note, the removal to a single callback updates the array first, before changing the static_call to single callback, which is the proper order as the first element in the array is the same as what the static_call is being changed to.
Link: https://lore.kernel.org/io-uring/4ebea8f0-58c9-e571-fd30-0ce4f6f09c70@samba.org/
Cc: stable@vger.kernel.org Fixes: d25e37d89dd2f ("tracepoint: Optimize using static_call()") Reported-by: Stefan Metzmacher <metze@samba.org> tested-by: Stefan Metzmacher <metze@samba.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
0531e84b |
| 29-Jun-2021 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
commit 9913d5745bd720c4266805c8d29952a3702e4eca upstream.
All internal use cases for tracepoint_probe_register() is set to not
tracepoint: Add tracepoint_probe_register_may_exist() for BPF tracing
commit 9913d5745bd720c4266805c8d29952a3702e4eca upstream.
All internal use cases for tracepoint_probe_register() is set to not ever be called with the same function and data. If it is, it is considered a bug, as that means the accounting of handling tracepoints is corrupted. If the function and data for a tracepoint is already registered when tracepoint_probe_register() is called, it will call WARN_ON_ONCE() and return with EEXISTS.
The BPF system call can end up calling tracepoint_probe_register() with the same data, which now means that this can trigger the warning because of a user space process. As WARN_ON_ONCE() should not be called because user space called a system call with bad data, there needs to be a way to register a tracepoint without triggering a warning.
Enter tracepoint_probe_register_may_exist(), which can be called, but will not cause a WARN_ON() if the probe already exists. It will still error out with EEXIST, which will then be sent to the user space that performed the BPF system call.
This keeps the previous testing for issues with other users of the tracepoint code, while letting BPF call it with duplicated data and not warn about it.
Link: https://lore.kernel.org/lkml/20210626135845.4080-1-penguin-kernel@I-love.SAKURA.ne.jp/ Link: https://syzkaller.appspot.com/bug?id=41f4318cf01762389f4d1c1c459da4f542fe5153
Cc: stable@vger.kernel.org Fixes: c4f6699dfcb85 ("bpf: introduce BPF_RAW_TRACEPOINT") Reported-by: syzbot <syzbot+721aa903751db87aa244@syzkaller.appspotmail.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: syzbot+721aa903751db87aa244@syzkaller.appspotmail.com Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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#
8a40ca0c |
| 18-Nov-2020 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoint: Do not fail unregistering a probe due to memory failure
[ Upstream commit befe6d946551d65cddbd32b9cb0170b0249fd5ed ]
The list of tracepoint callbacks is managed by an array that is prot
tracepoint: Do not fail unregistering a probe due to memory failure
[ Upstream commit befe6d946551d65cddbd32b9cb0170b0249fd5ed ]
The list of tracepoint callbacks is managed by an array that is protected by RCU. To update this array, a new array is allocated, the updates are copied over to the new array, and then the list of functions for the tracepoint is switched over to the new array. After a completion of an RCU grace period, the old array is freed.
This process happens for both adding a callback as well as removing one. But on removing a callback, if the new array fails to be allocated, the callback is not removed, and may be used after it is freed by the clients of the tracepoint.
There's really no reason to fail if the allocation for a new array fails when removing a function. Instead, the function can simply be replaced by a stub function that could be cleaned up on the next modification of the array. That is, instead of calling the function registered to the tracepoint, it would call a stub function in its place.
Link: https://lore.kernel.org/r/20201115055256.65625-1-mmullins@mmlx.us Link: https://lore.kernel.org/r/20201116175107.02db396d@gandalf.local.home Link: https://lore.kernel.org/r/20201117211836.54acaef2@oasis.local.home Link: https://lkml.kernel.org/r/20201118093405.7a6d2290@gandalf.local.home
[ Note, this version does use undefined compiler behavior (assuming that a stub function with no parameters or return, can be called by a location that thinks it has parameters but still no return value. Static calls do the same thing, so this trick is not without precedent.
There's another solution that uses RCU tricks and is more complex, but can be an alternative if this solution becomes an issue.
Link: https://lore.kernel.org/lkml/20210127170721.58bce7cc@gandalf.local.home/ ]
Cc: Peter Zijlstra <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Song Liu <songliubraving@fb.com> Cc: Yonghong Song <yhs@fb.com> Cc: Andrii Nakryiko <andriin@fb.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@chromium.org> Cc: netdev <netdev@vger.kernel.org> Cc: bpf <bpf@vger.kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Florian Weimer <fw@deneb.enyo.de> Fixes: 97e1c18e8d17b ("tracing: Kernel Tracepoints") Reported-by: syzbot+83aa762ef23b6f0d1991@syzkaller.appspotmail.com Reported-by: syzbot+d29e58bb557324e55e5e@syzkaller.appspotmail.com Reported-by: Matt Mullins <mmullins@mmlx.us> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Tested-by: Matt Mullins <mmullins@mmlx.us> Signed-off-by: Sasha Levin <sashal@kernel.org>
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Revision tags: v5.8.17, v5.8.16, v5.8.15, v5.9, v5.8.14, v5.8.13, v5.8.12, v5.8.11, v5.8.10, v5.8.9, v5.8.8, v5.8.7, v5.8.6, v5.4.62 |
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#
9d0a49c7 |
| 31-Aug-2020 |
Gustavo A. R. Silva <gustavoars@kernel.org> |
tracepoint: Replace zero-length array with flexible-array member
There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure.
tracepoint: Replace zero-length array with flexible-array member
There is a regular need in the kernel to provide a way to declare having a dynamically sized set of trailing elements in a structure. Kernel code should always use “flexible array members”[1] for these cases. The older style of one-element or zero-length arrays should no longer be used[2].
[1] https://en.wikipedia.org/wiki/Flexible_array_member [2] https://www.kernel.org/doc/html/v5.9-rc1/process/deprecated.html#zero-length-and-one-element-arrays
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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#
547305a6 |
| 01-Oct-2020 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoint: Fix out of sync data passing by static caller
Naresh reported a bug that appears to be a side effect of the static calls. It happens when going from more than one tracepoint callback to
tracepoint: Fix out of sync data passing by static caller
Naresh reported a bug that appears to be a side effect of the static calls. It happens when going from more than one tracepoint callback to a single one, and removing the first callback on the list. The list of tracepoint callbacks holds data and a function to call with the parameters of that tracepoint and a handler to the associated data.
old_list: 0: func = foo; data = NULL; 1: func = bar; data = &bar_struct;
new_list: 0: func = bar; data = &bar_struct;
CPU 0 CPU 1 ----- ----- tp_funcs = old_list; tp_static_caller = tp_interator
__DO_TRACE()
data = tp_funcs[0].data = NULL;
tp_funcs = new_list; tracepoint_update_call() tp_static_caller = tp_funcs[0] = bar; tp_static_caller(data) bar(data) x = data->item = NULL->item
BOOM!
To solve this, add a tracepoint_synchronize_unregister() between changing tp_funcs and updating the static tracepoint, that does both a synchronize_rcu() and synchronize_srcu(). This will ensure that when the static call is updated to the single callback that it will be receiving the data that it registered with.
Fixes: d25e37d89dd2f ("tracepoint: Optimize using static_call()") Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/linux-next/CA+G9fYvPXVRO0NV7yL=FxCmFEMYkCwdz7R=9W+_votpT824YJA@mail.gmail.com
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Revision tags: v5.8.5, v5.8.4, v5.4.61, v5.8.3, v5.4.60, v5.8.2, v5.4.59 |
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#
d25e37d8 |
| 18-Aug-2020 |
Steven Rostedt (VMware) <rostedt@goodmis.org> |
tracepoint: Optimize using static_call()
Currently the tracepoint site will iterate a vector and issue indirect calls to however many handlers are registered (ie. the vector is long).
Using static_
tracepoint: Optimize using static_call()
Currently the tracepoint site will iterate a vector and issue indirect calls to however many handlers are registered (ie. the vector is long).
Using static_call() it is possible to optimize this for the common case of only having a single handler registered. In this case the static_call() can directly call this handler. Otherwise, if the vector is longer than 1, call a function that iterates the whole vector like the current code.
[peterz: updated to new interface]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/r/20200818135805.279421092@infradead.org
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#
0340a6b7 |
| 18-Aug-2020 |
Peter Zijlstra <peterz@infradead.org> |
module: Fix up module_notifier return values
While auditing all module notifiers I noticed a whole bunch of fail wrt the return value. Notifiers have a 'special' return semantics.
As is; NOTIFY_DON
module: Fix up module_notifier return values
While auditing all module notifiers I noticed a whole bunch of fail wrt the return value. Notifiers have a 'special' return semantics.
As is; NOTIFY_DONE vs NOTIFY_OK is a bit vague; but notifier_from_errno(0) results in NOTIFY_OK and NOTIFY_DONE has a comment that says "Don't care".
From this I've used NOTIFY_DONE when the function completely ignores the callback and notifier_to_error() isn't used.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reviewed-by: Robert Richter <rric@kernel.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Link: https://lore.kernel.org/r/20200818135804.385360407@infradead.org
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Revision tags: v5.8.1, v5.4.58, v5.4.57, v5.4.56, v5.8, v5.7.12, v5.4.55, v5.7.11, v5.4.54, v5.7.10, v5.4.53, v5.4.52, v5.7.9, v5.7.8, v5.4.51, v5.4.50, v5.7.7, v5.4.49, v5.7.6, v5.7.5, v5.4.48, v5.7.4, v5.7.3, v5.4.47, v5.4.46, v5.7.2, v5.4.45, v5.7.1, v5.4.44, v5.7, v5.4.43, v5.4.42, v5.4.41, v5.4.40, v5.4.39, v5.4.38, v5.4.37, v5.4.36, v5.4.35, v5.4.34, v5.4.33, v5.4.32, v5.4.31, v5.4.30, v5.4.29, v5.6, v5.4.28, v5.4.27, v5.4.26, v5.4.25, v5.4.24, v5.4.23, v5.4.22, v5.4.21, v5.4.20, v5.4.19, v5.4.18, v5.4.17, v5.4.16, v5.5, v5.4.15, v5.4.14, v5.4.13, v5.4.12, v5.4.11, v5.4.10, v5.4.9, v5.4.8, v5.4.7, v5.4.6, v5.4.5, v5.4.4, v5.4.3, v5.3.15, v5.4.2, v5.4.1, v5.3.14, v5.4, v5.3.13, v5.3.12, v5.3.11, v5.3.10, v5.3.9, v5.3.8, v5.3.7, v5.3.6, v5.3.5, v5.3.4, v5.3.3, v5.3.2, v5.3.1, v5.3, v5.2.14, v5.3-rc8, v5.2.13, v5.2.12, v5.2.11, v5.2.10, v5.2.9, v5.2.8, v5.2.7, v5.2.6, v5.2.5, v5.2.4, v5.2.3, v5.2.2, v5.2.1, v5.2, v5.1.16, v5.1.15, v5.1.14, v5.1.13, v5.1.12, v5.1.11, v5.1.10, v5.1.9 |
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f0553dcb |
| 10-Jun-2019 |
Gustavo A. R. Silva <gustavo@embeddedor.com> |
tracepoint: Use struct_size() in kmalloc()
One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory f
tracepoint: Use struct_size() in kmalloc()
One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example:
struct tp_probes { ... struct tracepoint_func probes[0]; };
instance = kmalloc(sizeof(sizeof(struct tp_probes) + sizeof(struct tracepoint_func) * count, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper:
instance = kmalloc(struct_size(instance, probes, count) GFP_KERNEL);
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Revision tags: v5.1.8, v5.1.7, v5.1.6 |
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1a59d1b8 |
| 27-May-2019 |
Thomas Gleixner <tglx@linutronix.de> |
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify it under the terms of th
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1334 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Revision tags: v5.1.5, v5.1.4, v5.1.3, v5.1.2, v5.1.1, v5.0.14, v5.1, v5.0.13, v5.0.12, v5.0.11, v5.0.10, v5.0.9, v5.0.8, v5.0.7, v5.0.6, v5.0.5, v5.0.4, v5.0.3, v4.19.29, v5.0.2, v4.19.28, v5.0.1, v4.19.27, v5.0, v4.19.26, v4.19.25, v4.19.24, v4.19.23, v4.19.22, v4.19.21, v4.19.20, v4.19.19, v4.19.18, v4.19.17, v4.19.16, v4.19.15, v4.19.14, v4.19.13, v4.19.12, v4.19.11, v4.19.10, v4.19.9, v4.19.8, v4.19.7, v4.19.6, v4.19.5, v4.19.4, v4.18.20, v4.19.3, v4.18.19, v4.19.2, v4.18.18 |
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74401729 |
| 06-Nov-2018 |
Paul E. McKenney <paulmck@linux.ibm.com> |
tracing: Replace synchronize_sched() and call_rcu_sched()
Now that synchronize_rcu() waits for preempt-disable regions of code as well as RCU read-side critical sections, synchronize_sched() can be
tracing: Replace synchronize_sched() and call_rcu_sched()
Now that synchronize_rcu() waits for preempt-disable regions of code as well as RCU read-side critical sections, synchronize_sched() can be replaced by synchronize_rcu(). Similarly, call_rcu_sched() can be replaced by call_rcu(). This commit therefore makes these changes.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: <linux-kernel@vger.kernel.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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