rcutorture: Set KCSAN Kconfig options to detect more data races

This commit enables the KCSAN Kconfig options that (1) detect data
races between reads and writes even when the writes do not change t

rcutorture: Set KCSAN Kconfig options to detect more data races

This commit enables the KCSAN Kconfig options that (1) detect data
races between reads and writes even when the writes do not change the
variable's value and (2) detect data races involving plain C-language
writes. These changes only affect scripted rcutorture runs and can be
overridden using the kvm.sh --kconfig argument.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

show more ...

rcutorture: Tweak kvm options

In one of my rcutorture tests the TSC clocksource got marked unstable
due to a large difference in the TSC value. I'm not sure if the guest
run for a long time with dis

rcutorture: Tweak kvm options

In one of my rcutorture tests the TSC clocksource got marked unstable
due to a large difference in the TSC value. I'm not sure if the guest
run for a long time with disabled interrupts or if the host was very
busy and didn't schedule the guest for some time.

I took a look on the qemu/KVM options and decided to update the options:

- Use kvm{32|64} as CPU. We could probably use `host' (like ARM does)
for maximum available features but since we don't run any userland I'm
not sure if it makes any difference.

- Drop the "noapic" option. There is no history why the APIC was disabled,
I see no reason for it. Once old qemu versions fade away, we can add
"x2apic=on,tsc-deadline=on,hypervisor=on,tsc_adjust=on".

- Additional config options. It ensures that the kernel knowns that it
runs as a kvm guest and can use virt devices like the kvm-clock as
clocksource. The kvm-clock was the main motivation here.

- I didn't add a random HW device. It would make the random device ready
earlier (not it doesn't complete the initialisation at all) but I
doubt that there is any need for this.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ paulmck: The world is not quite ready for CONFIG_PARAVIRT_SPINLOCKS=y
and x2apic, so they are omitted for the time being. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

show more ...

torture: Add tests without slow grace period setup/cleanup

This commit moves CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP,
CONFIG_RCU_TORTURE_TEST_SLOW_INIT, and CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT
from CF

torture: Add tests without slow grace period setup/cleanup

This commit moves CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP,
CONFIG_RCU_TORTURE_TEST_SLOW_INIT, and CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT
from CFcommon to all of the TREE scenarios other than TREE08 and TREE09
in order to do at least some testing without these Kconfig options set.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

show more ...

rcu: Provide diagnostic option to slow down grace-period scans

Grace-period scans of the rcu_node combining tree normally
proceed quite quickly, so that it is very difficult to reproduce
races again

rcu: Provide diagnostic option to slow down grace-period scans

Grace-period scans of the rcu_node combining tree normally
proceed quite quickly, so that it is very difficult to reproduce
races against them. This commit therefore allows grace-period
pre-initialization and cleanup to be artificially slowed down,
increasing race-reproduction probability. A pair of pairs of new
Kconfig parameters are provided, RCU_TORTURE_TEST_SLOW_PREINIT to
enable the slowing down of propagating CPU-hotplug changes up the
combining tree along with RCU_TORTURE_TEST_SLOW_PREINIT_DELAY to
specify the delay in jiffies, and RCU_TORTURE_TEST_SLOW_CLEANUP
to enable the slowing down of the end-of-grace-period cleanup scan
along with RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY to specify the delay
in jiffies. Boot-time parameters named rcutree.gp_preinit_delay and
rcutree.gp_cleanup_delay allow these delays to be specified at boot time.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

show more ...

rcutorture: Enable slow grace-period initializations

This commit sets CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y, but leaves the
default time zero. This can be overridden by passing the
"--bootargs rcutre

rcutorture: Enable slow grace-period initializations

This commit sets CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y, but leaves the
default time zero. This can be overridden by passing the
"--bootargs rcutree.gp_init_delay=1" argument to kvm.sh.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

show more ...

rcutorture: Introduce "rcu" directory level underneath configs

This commit uses the standard software ploy of introducing another
level of indirection below the configs directory. This allows each

rcutorture: Introduce "rcu" directory level underneath configs

This commit uses the standard software ploy of introducing another
level of indirection below the configs directory. This allows each
torture-test suite to have its own set of Kconfig files, boot parameters,
and version-specific scripts. Initially, we have only rcu, but lock
will follow soonish.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

show more ...

rcutorture: Set KCSAN Kconfig options to detect more data races

This commit enables the KCSAN Kconfig options that (1) detect data
races between reads and writes even when the writes do

rcutorture: Set KCSAN Kconfig options to detect more data races

This commit enables the KCSAN Kconfig options that (1) detect data
races between reads and writes even when the writes do not change the
variable's value and (2) detect data races involving plain C-language
writes. These changes only affect scripted rcutorture runs and can be
overridden using the kvm.sh --kconfig argument.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

show more ...

rcutorture: Tweak kvm options

In one of my rcutorture tests the TSC clocksource got marked unstable
due to a large difference in the TSC value. I'm not sure if the guest
run for a lo

rcutorture: Tweak kvm options

In one of my rcutorture tests the TSC clocksource got marked unstable
due to a large difference in the TSC value. I'm not sure if the guest
run for a long time with disabled interrupts or if the host was very
busy and didn't schedule the guest for some time.

I took a look on the qemu/KVM options and decided to update the options:

- Use kvm{32|64} as CPU. We could probably use `host' (like ARM does)
for maximum available features but since we don't run any userland I'm
not sure if it makes any difference.

- Drop the "noapic" option. There is no history why the APIC was disabled,
I see no reason for it. Once old qemu versions fade away, we can add
"x2apic=on,tsc-deadline=on,hypervisor=on,tsc_adjust=on".

- Additional config options. It ensures that the kernel knowns that it
runs as a kvm guest and can use virt devices like the kvm-clock as
clocksource. The kvm-clock was the main motivation here.

- I didn't add a random HW device. It would make the random device ready
earlier (not it doesn't complete the initialisation at all) but I
doubt that there is any need for this.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ paulmck: The world is not quite ready for CONFIG_PARAVIRT_SPINLOCKS=y
and x2apic, so they are omitted for the time being. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

show more ...

torture: Add tests without slow grace period setup/cleanup

This commit moves CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP,
CONFIG_RCU_TORTURE_TEST_SLOW_INIT, and CONFIG_RCU_TORTURE_TEST_SLOW_PRE

torture: Add tests without slow grace period setup/cleanup

This commit moves CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP,
CONFIG_RCU_TORTURE_TEST_SLOW_INIT, and CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT
from CFcommon to all of the TREE scenarios other than TREE08 and TREE09
in order to do at least some testing without these Kconfig options set.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

show more ...

rcu: Provide diagnostic option to slow down grace-period scans

Grace-period scans of the rcu_node combining tree normally
proceed quite quickly, so that it is very difficult to reproduce

rcu: Provide diagnostic option to slow down grace-period scans

Grace-period scans of the rcu_node combining tree normally
proceed quite quickly, so that it is very difficult to reproduce
races against them. This commit therefore allows grace-period
pre-initialization and cleanup to be artificially slowed down,
increasing race-reproduction probability. A pair of pairs of new
Kconfig parameters are provided, RCU_TORTURE_TEST_SLOW_PREINIT to
enable the slowing down of propagating CPU-hotplug changes up the
combining tree along with RCU_TORTURE_TEST_SLOW_PREINIT_DELAY to
specify the delay in jiffies, and RCU_TORTURE_TEST_SLOW_CLEANUP
to enable the slowing down of the end-of-grace-period cleanup scan
along with RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY to specify the delay
in jiffies. Boot-time parameters named rcutree.gp_preinit_delay and
rcutree.gp_cleanup_delay allow these delays to be specified at boot time.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

show more ...

rcutorture: Enable slow grace-period initializations

This commit sets CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y, but leaves the
default time zero. This can be overridden by passing the
"-

rcutorture: Enable slow grace-period initializations

This commit sets CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y, but leaves the
default time zero. This can be overridden by passing the
"--bootargs rcutree.gp_init_delay=1" argument to kvm.sh.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

show more ...

rcutorture: Introduce "rcu" directory level underneath configs

This commit uses the standard software ploy of introducing another
level of indirection below the configs directory. This

rcutorture: Introduce "rcu" directory level underneath configs

This commit uses the standard software ploy of introducing another
level of indirection below the configs directory. This allows each
torture-test suite to have its own set of Kconfig files, boot parameters,
and version-specific scripts. Initially, we have only rcu, but lock
will follow soonish.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

show more ...