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| -rw-r--r-- | Documentation/DocBook/kernel-locking.tmpl | 25 |
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diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 77c42f40be5..2510763295d 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -703,6 +703,31 @@ </sect1> </chapter> +<chapter id="trylock-functions"> + <title>The trylock Functions</title> + <para> + 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. + </para> + + <para> + <function>spin_trylock()</function> 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 <function>spin_lock</function>: you must have + disabled the contexts that might interrupt you and acquire the spin lock. + </para> + + <para> + <function>mutex_trylock()</function> 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. + </para> +</chapter> + <chapter id="Examples"> <title>Common Examples</title> <para> |