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Peter Zijlstra authored
In order to direct the SIGIO signal to a particular thread of a multi-threaded application we cannot, like suggested by the manpage, put a TID into the regular fcntl(F_SETOWN) call. It will still be send to the whole process of which that thread is part. Since people do want to properly direct SIGIO we introduce F_SETOWN_EX. The need to direct SIGIO comes from self-monitoring profiling such as with perf-counters. Perf-counters uses SIGIO to notify that new sample data is available. If the signal is delivered to the same task that generated the new sample it can augment that data by inspecting the task's user-space state right after it returns from the kernel. This is esp. convenient for interpreted or virtual machine driven environments. Both F_SETOWN_EX and F_GETOWN_EX take a pointer to a struct f_owner_ex as argument: struct f_owner_ex { int type; pid_t pid; }; Where type is one of F_OWNER_TID, F_OWNER_PID or F_OWNER_GID. Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Reviewed-by:
Oleg Nesterov <oleg@redhat.com> Tested-by:
stephane eranian <eranian@googlemail.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Roland McGrath <roland@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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