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Commit 1791f881 authored by Richard Cochran's avatar Richard Cochran Committed by Thomas Gleixner
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posix clocks: Replace mutex with reader/writer semaphore



A dynamic posix clock is protected from asynchronous removal by a mutex.
However, using a mutex has the unwanted effect that a long running clock
operation in one process will unnecessarily block other processes.

For example, one process might call read() to get an external time stamp
coming in at one pulse per second. A second process calling clock_gettime
would have to wait for almost a whole second.

This patch fixes the issue by using a reader/writer semaphore instead of
a mutex.

Signed-off-by: default avatarRichard Cochran <richard.cochran@omicron.at>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/%3C20110330132421.GA31771%40riccoc20.at.omicron.at%3E


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent a1b49cb7
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