perf: Fix fasync handling on inherited events
commit fed66e2c upstream. Vince reported that the fasync signal stuff doesn't work proper for inherited events. So fix that. Installing fasync allocates memory and sets filp->f_flags |= FASYNC, which upon the demise of the file descriptor ensures the allocation is freed and state is updated. Now for perf, we can have the events stick around for a while after the original FD is dead because of references from child events. So we cannot copy the fasync pointer around. We can however consistently use the parent's fasync, as that will be updated. Reported-and-Tested-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho deMelo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: eranian@google.com Link: http://lkml.kernel.org/r/1434011521.1495.71.camel@twinsSigned-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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