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authorThomas Gleixner <tglx@linutronix.de>2013-05-28 07:33:01 (GMT)
committerThomas Gleixner <tglx@linutronix.de>2013-05-28 07:33:01 (GMT)
commit2938d2757fc99c26aa678ce4eba910c4a77c3a55 (patch)
tree67a083021705f6cac75f6bea2fa83e975807c624 /kernel/nsproxy.c
parente4aa937ec75df0eea0bee03bffa3303ad36c986b (diff)
downloadlinux-2938d2757fc99c26aa678ce4eba910c4a77c3a55.tar.xz
tick: Cure broadcast false positive pending bit warning
commit 26517f3e (tick: Avoid programming the local cpu timer if broadcast pending) added a warning if the cpu enters broadcast mode again while the pending bit is still set. Meelis reported that the warning triggers. There are two corner cases which have been not considered: 1) cpuidle calls clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER) twice. That can result in the following scenario CPU0 CPU1 cpuidle_idle_call() clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER) set cpu in tick_broadcast_oneshot_mask broadcast interrupt event expired for cpu1 set pending bit acpi_idle_enter_simple() clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER) WARN_ON(pending bit) Move the WARN_ON into the section where we enter broadcast mode so it wont provide false positives on the second call. 2) safe_halt() enables interrupts, so a broadcast interrupt can be delivered befor the broadcast mode is disabled. That sets the pending bit for the CPU which receives the broadcast interrupt. Though the interrupt is delivered right away from the broadcast handler and leaves the pending bit stale. Clear the pending bit for the current cpu in the broadcast handler. Reported-and-tested-by: Meelis Roos <mroos@linux.ee> Cc: Len Brown <lenb@kernel.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Rafael J. Wysocki <rjw@sisk.pl> Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1305271841130.4220@ionos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/nsproxy.c')
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