From: Matti Linnanvuori Date: Tue, 13 May 2008 15:31:47 +0000 (+0300) Subject: doc: add a chapter about trylock functions [Bug 9011] X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4d2e7d0d77e4e1e8a21cc990c607985fdba20e66;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git doc: add a chapter about trylock functions [Bug 9011] Add a chapter about trylock functions. http://bugzilla.kernel.org/show_bug.cgi?id=9011 Signed-off-by: Matti Linnanvuori Signed-off-by: Rusty Russell (removed down_trylock) --- diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 77c42f40be5d..2510763295d0 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -703,6 +703,31 @@ + + The trylock Functions + + There are functions that try to acquire a lock only once and immediately + return a value telling about success or failure to acquire the lock. + They can be used if you need no access to the data protected with the lock + when some other thread is holding the lock. You should acquire the lock + later if you then need access to the data protected with the lock. + + + + spin_trylock() does not spin but returns non-zero if + it acquires the spinlock on the first try or 0 if not. This function can + be used in all contexts like spin_lock: you must have + disabled the contexts that might interrupt you and acquire the spin lock. + + + + mutex_trylock() does not suspend your task + but returns non-zero if it could lock the mutex on the first try + or 0 if not. This function cannot be safely used in hardware or software + interrupt contexts despite not sleeping. + + + Common Examples