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authorMiroslav Benes <mbenes@suse.cz>2019-01-15 17:45:06 +0100
committerJiri Kosina <jkosina@suse.cz>2019-01-16 22:09:09 +0100
commitcba82dea30613346cf9a0532a41fc118bc3263af (patch)
treec7b4182b5f7bc83b646eae084d4a6646f3da874b /Documentation/livepatch
parenta2818ee4dce575b299d8a7f46b393bc2b02ef1f4 (diff)
downloadlinux-cba82dea30613346cf9a0532a41fc118bc3263af.tar.bz2
livepatch: Send a fake signal periodically
An administrator may send a fake signal to all remaining blocking tasks of a running transition by writing to /sys/kernel/livepatch/<patch>/signal attribute. Let's do it automatically after 15 seconds. The timeout is chosen deliberately. It gives the tasks enough time to transition themselves. Theoretically, sending it once should be more than enough. However, every task must get outside of a patched function to be successfully transitioned. It could prove not to be simple and resending could be helpful in that case. A new workqueue job could be a cleaner solution to achieve it, but it could also introduce deadlocks and cause more headaches with synchronization and cancelling. [jkosina@suse.cz: removed added newline] Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'Documentation/livepatch')
-rw-r--r--Documentation/livepatch/livepatch.txt3
1 files changed, 2 insertions, 1 deletions
diff --git a/Documentation/livepatch/livepatch.txt b/Documentation/livepatch/livepatch.txt
index 71d7f286ec4d..407e0f03dc99 100644
--- a/Documentation/livepatch/livepatch.txt
+++ b/Documentation/livepatch/livepatch.txt
@@ -163,7 +163,8 @@ patched state. This may be harmful to the system though.
Writing 1 to the attribute sends a fake signal to all remaining blocking
tasks. No proper signal is actually delivered (there is no data in signal
pending structures). Tasks are interrupted or woken up, and forced to change
-their patched state.
+their patched state. Despite the sysfs attribute the fake signal is also sent
+every 15 seconds automatically.
Administrator can also affect a transition through
/sys/kernel/livepatch/<patch>/force attribute. Writing 1 there clears