From: Jason Low Date: Wed, 11 Jun 2014 18:37:21 +0000 (-0700) Subject: locking/mutexes: Delete the MUTEX_SHOW_NO_WAITER macro X-Git-Tag: omap-for-v3.17/fixes-against-rc2~179^2~5 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1e820c9608eace237e2c519d8fd9074aec479d81;p=pandora-kernel.git locking/mutexes: Delete the MUTEX_SHOW_NO_WAITER macro MUTEX_SHOW_NO_WAITER() is a macro which checks for if there are "no waiters" on a mutex by checking if the lock count is non-negative. Based on feedback from the discussion in the earlier version of this patchset, the macro is not very readable. Furthermore, checking lock->count isn't always the correct way to determine if there are "no waiters" on a mutex. For example, a negative count on a mutex really only means that there "potentially" are waiters. Likewise, there can be waiters on the mutex even if the count is non-negative. Thus, "MUTEX_SHOW_NO_WAITER" doesn't always do what the name of the macro suggests. So this patch deletes the MUTEX_SHOW_NO_WAITERS() macro, directly use atomic_read() instead of the macro, and adds comments which elaborate on how the extra atomic_read() checks can help reduce unnecessary xchg() operations. Signed-off-by: Jason Low Acked-by: Waiman Long Signed-off-by: Peter Zijlstra Cc: akpm@linux-foundation.org Cc: tim.c.chen@linux.intel.com Cc: paulmck@linux.vnet.ibm.com Cc: rostedt@goodmis.org Cc: davidlohr@hp.com Cc: scott.norton@hp.com Cc: aswin@hp.com Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1402511843-4721-3-git-send-email-jason.low2@hp.com Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed