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, 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, v5.15.67, v5.15.66, v5.15.65, v5.15.64, v5.15.63, v5.15.62, v5.15.61, v5.15.60 |
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#
32ad1112 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a po
xen/xenbus: fix return type in xenbus_file_read()
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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#
75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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75b81010 |
| 04-Aug-2022 |
Dan Carpenter <dan.carpenter@oracle.com> |
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function ret
xen/xenbus: fix return type in xenbus_file_read()
commit 32ad11127b95236dfc52375f3707853194a7f4b4 upstream.
This code tries to store -EFAULT in an unsigned int. The xenbus_file_read() function returns type ssize_t so the negative value is returned as a positive value to the user.
This change forces another change to the min() macro. Originally, the min() macro used "unsigned" type which checkpatch complains about. Also unsigned type would break if "len" were not capped at MAX_RW_COUNT. Use size_t for the min(). (No effect on runtime for the min_t() change).
Fixes: 2fb3683e7b16 ("xen: Add xenbus device driver") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Link: https://lore.kernel.org/r/YutxJUaUYRG/VLVc@kili Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
show more ...
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Revision tags: 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, v5.10.53, v5.10.52, v5.10.51, v5.10.50, v5.10.49, 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, v5.10, 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, v5.8.5, v5.8.4, v5.4.61, v5.8.3, v5.4.60, v5.8.2, v5.4.59, 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 |
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#
a8fabb38 |
| 01-Oct-2019 |
Juergen Gross <jgross@suse.com> |
xen/xenbus: fix self-deadlock after killing user process
In case a user process using xenbus has open transactions and is killed e.g. via ctrl-C the following cleanup of the allocated resources migh
xen/xenbus: fix self-deadlock after killing user process
In case a user process using xenbus has open transactions and is killed e.g. via ctrl-C the following cleanup of the allocated resources might result in a deadlock due to trying to end a transaction in the xenbus worker thread:
[ 2551.474706] INFO: task xenbus:37 blocked for more than 120 seconds. [ 2551.492215] Tainted: P OE 5.0.0-29-generic #5 [ 2551.510263] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 2551.528585] xenbus D 0 37 2 0x80000080 [ 2551.528590] Call Trace: [ 2551.528603] __schedule+0x2c0/0x870 [ 2551.528606] ? _cond_resched+0x19/0x40 [ 2551.528632] schedule+0x2c/0x70 [ 2551.528637] xs_talkv+0x1ec/0x2b0 [ 2551.528642] ? wait_woken+0x80/0x80 [ 2551.528645] xs_single+0x53/0x80 [ 2551.528648] xenbus_transaction_end+0x3b/0x70 [ 2551.528651] xenbus_file_free+0x5a/0x160 [ 2551.528654] xenbus_dev_queue_reply+0xc4/0x220 [ 2551.528657] xenbus_thread+0x7de/0x880 [ 2551.528660] ? wait_woken+0x80/0x80 [ 2551.528665] kthread+0x121/0x140 [ 2551.528667] ? xb_read+0x1d0/0x1d0 [ 2551.528670] ? kthread_park+0x90/0x90 [ 2551.528673] ret_from_fork+0x35/0x40
Fix this by doing the cleanup via a workqueue instead.
Reported-by: James Dingwall <james@dingwall.me.uk> Fixes: fd8aa9095a95c ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") Cc: <stable@vger.kernel.org> # 4.11 Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Revision tags: 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, v5.1.8, v5.1.7, v5.1.6, v5.1.5, v5.1.4, v5.1.3, v5.1.2 |
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#
d10e0cc1 |
| 13-May-2019 |
Ross Lagerwall <ross.lagerwall@citrix.com> |
xenbus: Avoid deadlock during suspend due to open transactions
During a suspend/resume, the xenwatch thread waits for all outstanding xenstore requests and transactions to complete. This does not wo
xenbus: Avoid deadlock during suspend due to open transactions
During a suspend/resume, the xenwatch thread waits for all outstanding xenstore requests and transactions to complete. This does not work correctly for transactions started by userspace because it waits for them to complete after freezing userspace threads which means the transactions have no way of completing, resulting in a deadlock. This is trivial to reproduce by running this script and then suspending the VM:
import pyxs, time c = pyxs.client.Client(xen_bus_path="/dev/xen/xenbus") c.connect() c.transaction() time.sleep(3600)
Even if this deadlock were resolved, misbehaving userspace should not prevent a VM from being migrated. So, instead of waiting for these transactions to complete before suspending, store the current generation id for each transaction when it is started. The global generation id is incremented during resume. If the caller commits the transaction and the generation id does not match the current generation id, return EAGAIN so that they try again. If the transaction was instead discarded, return OK since no changes were made anyway.
This only affects users of the xenbus file interface. In-kernel users of xenbus are assumed to be well-behaved and complete all transactions before freezing.
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Revision tags: 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 |
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51cf07a7 |
| 15-Apr-2019 |
Mao Wenan <maowenan@huawei.com> |
xenbus: drop useless LIST_HEAD in xenbus_write_watch() and xenbus_file_write()
Drop LIST_HEAD where the variable it declares is never used.
The declarations were introduced with the file, but the d
xenbus: drop useless LIST_HEAD in xenbus_write_watch() and xenbus_file_write()
Drop LIST_HEAD where the variable it declares is never used.
The declarations were introduced with the file, but the declared variables were not used.
Fixes: 1107ba885e469 ("xen: add xenfs to allow usermode <-> Xen interaction") Signed-off-by: Mao Wenan <maowenan@huawei.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Revision tags: v5.0.7, v5.0.6, v5.0.5 |
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#
10dce8af |
| 26-Mar-2019 |
Kirill Smelkov <kirr@nexedi.com> |
fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock
Commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per POSIX") added locking for file.f
fs: stream_open - opener for stream-like files so that read and write can run simultaneously without deadlock
Commit 9c225f2655e3 ("vfs: atomic f_pos accesses as per POSIX") added locking for file.f_pos access and in particular made concurrent read and write not possible - now both those functions take f_pos lock for the whole run, and so if e.g. a read is blocked waiting for data, write will deadlock waiting for that read to complete.
This caused regression for stream-like files where previously read and write could run simultaneously, but after that patch could not do so anymore. See e.g. commit 581d21a2d02a ("xenbus: fix deadlock on writes to /proc/xen/xenbus") which fixes such regression for particular case of /proc/xen/xenbus.
The patch that added f_pos lock in 2014 did so to guarantee POSIX thread safety for read/write/lseek and added the locking to file descriptors of all regular files. In 2014 that thread-safety problem was not new as it was already discussed earlier in 2006.
However even though 2006'th version of Linus's patch was adding f_pos locking "only for files that are marked seekable with FMODE_LSEEK (thus avoiding the stream-like objects like pipes and sockets)", the 2014 version - the one that actually made it into the tree as 9c225f2655e3 - is doing so irregardless of whether a file is seekable or not.
See
https://lore.kernel.org/lkml/53022DB1.4070805@gmail.com/ https://lwn.net/Articles/180387 https://lwn.net/Articles/180396
for historic context.
The reason that it did so is, probably, that there are many files that are marked non-seekable, but e.g. their read implementation actually depends on knowing current position to correctly handle the read. Some examples:
kernel/power/user.c snapshot_read fs/debugfs/file.c u32_array_read fs/fuse/control.c fuse_conn_waiting_read + ... drivers/hwmon/asus_atk0110.c atk_debugfs_ggrp_read arch/s390/hypfs/inode.c hypfs_read_iter ...
Despite that, many nonseekable_open users implement read and write with pure stream semantics - they don't depend on passed ppos at all. And for those cases where read could wait for something inside, it creates a situation similar to xenbus - the write could be never made to go until read is done, and read is waiting for some, potentially external, event, for potentially unbounded time -> deadlock.
Besides xenbus, there are 14 such places in the kernel that I've found with semantic patch (see below):
drivers/xen/evtchn.c:667:8-24: ERROR: evtchn_fops: .read() can deadlock .write() drivers/isdn/capi/capi.c:963:8-24: ERROR: capi_fops: .read() can deadlock .write() drivers/input/evdev.c:527:1-17: ERROR: evdev_fops: .read() can deadlock .write() drivers/char/pcmcia/cm4000_cs.c:1685:7-23: ERROR: cm4000_fops: .read() can deadlock .write() net/rfkill/core.c:1146:8-24: ERROR: rfkill_fops: .read() can deadlock .write() drivers/s390/char/fs3270.c:488:1-17: ERROR: fs3270_fops: .read() can deadlock .write() drivers/usb/misc/ldusb.c:310:1-17: ERROR: ld_usb_fops: .read() can deadlock .write() drivers/hid/uhid.c:635:1-17: ERROR: uhid_fops: .read() can deadlock .write() net/batman-adv/icmp_socket.c:80:1-17: ERROR: batadv_fops: .read() can deadlock .write() drivers/media/rc/lirc_dev.c:198:1-17: ERROR: lirc_fops: .read() can deadlock .write() drivers/leds/uleds.c:77:1-17: ERROR: uleds_fops: .read() can deadlock .write() drivers/input/misc/uinput.c:400:1-17: ERROR: uinput_fops: .read() can deadlock .write() drivers/infiniband/core/user_mad.c:985:7-23: ERROR: umad_fops: .read() can deadlock .write() drivers/gnss/core.c:45:1-17: ERROR: gnss_fops: .read() can deadlock .write()
In addition to the cases above another regression caused by f_pos locking is that now FUSE filesystems that implement open with FOPEN_NONSEEKABLE flag, can no longer implement bidirectional stream-like files - for the same reason as above e.g. read can deadlock write locking on file.f_pos in the kernel.
FUSE's FOPEN_NONSEEKABLE was added in 2008 in a7c1b990f715 ("fuse: implement nonseekable open") to support OSSPD. OSSPD implements /dev/dsp in userspace with FOPEN_NONSEEKABLE flag, with corresponding read and write routines not depending on current position at all, and with both read and write being potentially blocking operations:
See
https://github.com/libfuse/osspd https://lwn.net/Articles/308445
https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1406 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1438-L1477 https://github.com/libfuse/osspd/blob/14a9cff0/osspd.c#L1479-L1510
Corresponding libfuse example/test also describes FOPEN_NONSEEKABLE as "somewhat pipe-like files ..." with read handler not using offset. However that test implements only read without write and cannot exercise the deadlock scenario:
https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L124-L131 https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L146-L163 https://github.com/libfuse/libfuse/blob/fuse-3.4.2-3-ga1bff7d/example/poll.c#L209-L216
I've actually hit the read vs write deadlock for real while implementing my FUSE filesystem where there is /head/watch file, for which open creates separate bidirectional socket-like stream in between filesystem and its user with both read and write being later performed simultaneously. And there it is semantically not easy to split the stream into two separate read-only and write-only channels:
https://lab.nexedi.com/kirr/wendelin.core/blob/f13aa600/wcfs/wcfs.go#L88-169
Let's fix this regression. The plan is:
1. We can't change nonseekable_open to include &~FMODE_ATOMIC_POS - doing so would break many in-kernel nonseekable_open users which actually use ppos in read/write handlers.
2. Add stream_open() to kernel to open stream-like non-seekable file descriptors. Read and write on such file descriptors would never use nor change ppos. And with that property on stream-like files read and write will be running without taking f_pos lock - i.e. read and write could be running simultaneously.
3. With semantic patch search and convert to stream_open all in-kernel nonseekable_open users for which read and write actually do not depend on ppos and where there is no other methods in file_operations which assume @offset access.
4. Add FOPEN_STREAM to fs/fuse/ and open in-kernel file-descriptors via steam_open if that bit is present in filesystem open reply.
It was tempting to change fs/fuse/ open handler to use stream_open instead of nonseekable_open on just FOPEN_NONSEEKABLE flags, but grepping through Debian codesearch shows users of FOPEN_NONSEEKABLE, and in particular GVFS which actually uses offset in its read and write handlers
https://codesearch.debian.net/search?q=-%3Enonseekable+%3D https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1080 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1247-1346 https://gitlab.gnome.org/GNOME/gvfs/blob/1.40.0-6-gcbc54396/client/gvfsfusedaemon.c#L1399-1481
so if we would do such a change it will break a real user.
5. Add stream_open and FOPEN_STREAM handling to stable kernels starting from v3.14+ (the kernel where 9c225f2655 first appeared).
This will allow to patch OSSPD and other FUSE filesystems that provide stream-like files to return FOPEN_STREAM | FOPEN_NONSEEKABLE in their open handler and this way avoid the deadlock on all kernel versions. This should work because fs/fuse/ ignores unknown open flags returned from a filesystem and so passing FOPEN_STREAM to a kernel that is not aware of this flag cannot hurt. In turn the kernel that is not aware of FOPEN_STREAM will be < v3.14 where just FOPEN_NONSEEKABLE is sufficient to implement streams without read vs write deadlock.
This patch adds stream_open, converts /proc/xen/xenbus to it and adds semantic patch to automatically locate in-kernel places that are either required to be converted due to read vs write deadlock, or that are just safe to be converted because read and write do not use ppos and there are no other funky methods in file_operations.
Regarding semantic patch I've verified each generated change manually - that it is correct to convert - and each other nonseekable_open instance left - that it is either not correct to convert there, or that it is not converted due to current stream_open.cocci limitations.
The script also does not convert files that should be valid to convert, but that currently have .llseek = noop_llseek or generic_file_llseek for unknown reason despite file being opened with nonseekable_open (e.g. drivers/input/mousedev.c)
Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Yongzhi Pan <panyongzhi@gmail.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Tejun Heo <tj@kernel.org> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Julia Lawall <Julia.Lawall@lip6.fr> Cc: Nikolaus Rath <Nikolaus@rath.org> Cc: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Kirill Smelkov <kirr@nexedi.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Revision tags: 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, v4.18.17, v4.19.1, v4.19, v4.18.16, v4.18.15, v4.18.14, v4.18.13, v4.18.12, v4.18.11, v4.18.10, v4.18.9, v4.18.7, v4.18.6, v4.18.5, v4.17.18, v4.18.4, v4.18.3, v4.17.17, v4.18.2, v4.17.16, v4.17.15, v4.18.1, v4.18, v4.17.14, v4.17.13, v4.17.12, v4.17.11, v4.17.10, v4.17.9, v4.17.8, v4.17.7, v4.17.6, v4.17.5, v4.17.4, v4.17.3, v4.17.2, v4.17.1, v4.17, v4.16 |
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#
ebf04f33 |
| 14-Mar-2018 |
Simon Gaiser <simon@invisiblethingslab.com> |
xen: xenbus_dev_frontend: Really return response string
xenbus_command_reply() did not actually copy the response string and leaked stack content instead.
Fixes: 9a6161fe73bd ("xen: return xenstore
xen: xenbus_dev_frontend: Really return response string
xenbus_command_reply() did not actually copy the response string and leaked stack content instead.
Fixes: 9a6161fe73bd ("xen: return xenstore command failures via response instead of rc") Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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#
8fe5ab41 |
| 14-Mar-2018 |
Simon Gaiser <simon@invisiblethingslab.com> |
xen: xenbus_dev_frontend: Verify body of XS_TRANSACTION_END
By guaranteeing that the argument of XS_TRANSACTION_END is valid we can assume that the transaction has been closed when we get an XS_ERRO
xen: xenbus_dev_frontend: Verify body of XS_TRANSACTION_END
By guaranteeing that the argument of XS_TRANSACTION_END is valid we can assume that the transaction has been closed when we get an XS_ERROR response from xenstore (Note that we already verify that it's a valid transaction id).
Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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#
2a22ee6c |
| 14-Mar-2018 |
Simon Gaiser <simon@invisiblethingslab.com> |
xen: xenbus_dev_frontend: Fix XS_TRANSACTION_END handling
Commit fd8aa9095a95 ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") made a subtle change to the semantic of xenbus
xen: xenbus_dev_frontend: Fix XS_TRANSACTION_END handling
Commit fd8aa9095a95 ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") made a subtle change to the semantic of xenbus_dev_request_and_reply() and xenbus_transaction_end().
Before on an error response to XS_TRANSACTION_END xenbus_dev_request_and_reply() would not decrement the active transaction counter. But xenbus_transaction_end() has always counted the transaction as finished regardless of the response.
The new behavior is that xenbus_dev_request_and_reply() and xenbus_transaction_end() will always count the transaction as finished regardless the response code (handled in xs_request_exit()).
But xenbus_dev_frontend tries to end a transaction on closing of the device if the XS_TRANSACTION_END failed before. Trying to close the transaction twice corrupts the reference count. So fix this by also considering a transaction closed if we have sent XS_TRANSACTION_END once regardless of the return code.
Cc: <stable@vger.kernel.org> # 4.11 Fixes: fd8aa9095a95 ("xen: optimize xenbus driver for multiple concurrent xenstore accesses") Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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#
a9a08845 |
| 11-Feb-2018 |
Linus Torvalds <torvalds@linux-foundation.org> |
vfs: do bulk POLL* -> EPOLL* replacement
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script:
for V in IN OUT PRI ERR RDNORM RDBAN
vfs: do bulk POLL* -> EPOLL* replacement
This is the mindless scripted replacement of kernel use of POLL* variables as described by Al, done by this script:
for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'` for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done done
with de-mangling cleanups yet to come.
NOTE! On almost all architectures, the EPOLL* constants have the same values as the POLL* constants do. But they keyword here is "almost". For various bad reasons they aren't the same, and epoll() doesn't actually work quite correctly in some cases due to this on Sparc et al.
The next patch from Al will sort out the final differences, and we should be all done.
Scripted-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Revision tags: v4.15, v4.13.16, v4.14, v4.13.5, v4.13 |
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#
afc9a42b |
| 03-Jul-2017 |
Al Viro <viro@zeniv.linux.org.uk> |
the rest of drivers/*: annotate ->poll() instances
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Revision tags: v4.12, v4.10.17, v4.10.16, v4.10.15, v4.10.14, v4.10.13, v4.10.12, v4.10.11, v4.10.10, v4.10.9 |
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#
ac4cde39 |
| 04-Apr-2017 |
Jan Beulich <JBeulich@suse.com> |
xenbus: remove transaction holder from list before freeing
After allocation the item is being placed on the list right away. Consequently it needs to be taken off the list before freeing in the case
xenbus: remove transaction holder from list before freeing
After allocation the item is being placed on the list right away. Consequently it needs to be taken off the list before freeing in the case xenbus_dev_request_and_reply() failed, as in that case the callback (xenbus_dev_queue_reply()) is not being called (and if it was called, it should do both).
Fixes: 5584ea250ae44f929feb4c7bd3877d1c5edbf813 Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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Revision tags: v4.10.8, v4.10.7, v4.10.6, v4.10.5, v4.10.4, v4.10.3, v4.10.2, v4.10.1 |
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#
d825adb4 |
| 26-Feb-2017 |
Masanari Iida <standby24x7@gmail.com> |
xenbus: Remove duplicate inclusion of linux/init.h
This patch remove duplicate inclusion of linux/init.h in xenbus_dev_frontend.c. Confirm successfully compile after remove the line.
Signed-off-by:
xenbus: Remove duplicate inclusion of linux/init.h
This patch remove duplicate inclusion of linux/init.h in xenbus_dev_frontend.c. Confirm successfully compile after remove the line.
Signed-off-by: Masanari Iida <standby24x7@gmail.com> Reviewed-by: Juergen Gross <jgross@suse.com>
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Revision tags: v4.10 |
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#
fd8aa909 |
| 09-Feb-2017 |
Juergen Gross <jgross@suse.com> |
xen: optimize xenbus driver for multiple concurrent xenstore accesses
Handling of multiple concurrent Xenstore accesses through xenbus driver either from the kernel or user land is rather lame today
xen: optimize xenbus driver for multiple concurrent xenstore accesses
Handling of multiple concurrent Xenstore accesses through xenbus driver either from the kernel or user land is rather lame today: xenbus is capable to have one access active only at one point of time.
Rewrite xenbus to handle multiple requests concurrently by making use of the request id of the Xenstore protocol. This requires to:
- Instead of blocking inside xb_read() when trying to read data from the xenstore ring buffer do so only in the main loop of xenbus_thread().
- Instead of doing writes to the xenstore ring buffer in the context of the caller just queue the request and do the write in the dedicated xenbus thread.
- Instead of just forwarding the request id specified by the caller of xenbus to xenstore use a xenbus internal unique request id. This will allow multiple outstanding requests.
- Modify the locking scheme in order to allow multiple requests being active in parallel.
- Instead of waiting for the reply of a user's xenstore request after writing the request to the xenstore ring buffer return directly to the caller and do the waiting in the read path.
Additionally signal handling was optimized by avoiding waking up the xenbus thread or sending an event to Xenstore in case the addressed entity is known to be running already.
As a result communication with Xenstore is sped up by a factor of up to 5: depending on the request type (read or write) and the amount of data transferred the gain was at least 20% (small reads) and went up to a factor of 5 for large writes.
In the end some more rough edges of xenbus have been smoothed:
- Handling of memory shortage when reading from xenstore ring buffer in the xenbus driver was not optimal: it was busy looping and issuing a warning in each loop.
- In case of xenstore not running in dom0 but in a stubdom we end up with two xenbus threads running as the initialization of xenbus in dom0 expecting a local xenstored will be redone later when connecting to the xenstore domain. Up to now this was no problem as locking would prevent the two xenbus threads interfering with each other, but this was just a waste of kernel resources.
- An out of memory situation while writing to or reading from the xenstore ring buffer no longer will lead to a possible loss of synchronization with xenstore.
- The user read and write part are now interruptible by signals.
Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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#
5584ea25 |
| 09-Feb-2017 |
Juergen Gross <jgross@suse.com> |
xen: modify xenstore watch event interface
Today a Xenstore watch event is delivered via a callback function declared as:
void (*callback)(struct xenbus_watch *, const char **vec,
xen: modify xenstore watch event interface
Today a Xenstore watch event is delivered via a callback function declared as:
void (*callback)(struct xenbus_watch *, const char **vec, unsigned int len);
As all watch events only ever come with two parameters (path and token) changing the prototype to:
void (*callback)(struct xenbus_watch *, const char *path, const char *token);
is the natural thing to do.
Apply this change and adapt all users.
Cc: konrad.wilk@oracle.com Cc: roger.pau@citrix.com Cc: wei.liu2@citrix.com Cc: paul.durrant@citrix.com Cc: netdev@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Paul Durrant <paul.durrant@citrix.com> Reviewed-by: Wei Liu <wei.liu2@citrix.com> Reviewed-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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#
332f791d |
| 09-Feb-2017 |
Juergen Gross <jgross@suse.com> |
xen: clean up xenbus internal headers
The xenbus driver has an awful mixture of internally and globally visible headers: some of the internally used only stuff is defined in the global header includ
xen: clean up xenbus internal headers
The xenbus driver has an awful mixture of internally and globally visible headers: some of the internally used only stuff is defined in the global header include/xen/xenbus.h while some stuff defined in internal headers is used by other drivers, too.
Clean this up by moving the externally used symbols to include/xen/xenbus.h and the symbols used internally only to a new header drivers/xen/xenbus/xenbus.h replacing xenbus_comms.h and xenbus_probe.h
Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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#
9a6161fe |
| 22-Dec-2016 |
Juergen Gross <jgross@suse.com> |
xen: return xenstore command failures via response instead of rc
When the xenbus driver does some special handling for a Xenstore command any error condition related to the command should be returne
xen: return xenstore command failures via response instead of rc
When the xenbus driver does some special handling for a Xenstore command any error condition related to the command should be returned via an error response instead of letting the related write operation fail. Otherwise the user land handler might take wrong decisions assuming the connection to Xenstore is broken.
While at it try to return the same error values xenstored would return for those cases.
Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Signed-off-by: Juergen Gross <jgross@suse.com>
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