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authorWang YanQing <[email protected]>2013-01-26 15:53:57 +0800
committerIngo Molnar <[email protected]>2013-01-28 11:21:57 +0100
commitf44310b98ddb7f0d06550d73ed67df5865e3eda5 (patch)
tree77696b4312a7450afcc24c478df4721eda2f777f /net/lapb
parentc903f0456bc69176912dee6dd25c6a66ee1aed00 (diff)
smp: Fix SMP function call empty cpu mask race
I get the following warning every day with v3.7, once or twice a day: [ 2235.186027] WARNING: at /mnt/sda7/kernel/linux/arch/x86/kernel/apic/ipi.c:109 default_send_IPI_mask_logical+0x2f/0xb8() As explained by Linus as well: | | Once we've done the "list_add_rcu()" to add it to the | queue, we can have (another) IPI to the target CPU that can | now see it and clear the mask. | | So by the time we get to actually send the IPI, the mask might | have been cleared by another IPI. | This patch also fixes a system hang problem, if the data->cpumask gets cleared after passing this point: if (WARN_ONCE(!mask, "empty IPI mask")) return; then the problem in commit 83d349f35e1a ("x86: don't send an IPI to the empty set of CPU's") will happen again. Signed-off-by: Wang YanQing <[email protected]> Acked-by: Linus Torvalds <[email protected]> Acked-by: Jan Beulich <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: Andrew Morton <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: <[email protected]> Link: http://lkml.kernel.org/r/20130126075357.GA3205@udknight [ Tidied up the changelog and the comment in the code. ] Signed-off-by: Ingo Molnar <[email protected]>
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