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author | David S. Miller <davem@davemloft.net> | 2008-06-10 09:22:26 (GMT) |
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committer | David S. Miller <davem@davemloft.net> | 2008-06-10 09:22:26 (GMT) |
commit | 65b53e4cc90e59936733b3b95b9451d2ca47528d (patch) | |
tree | 29932718192962671c48c3fd1ea017a6112459e8 /Documentation/DocBook/kernel-locking.tmpl | |
parent | 788c0a53164c05c5ccdb1472474372b72ba74644 (diff) | |
parent | 2e761e0532a784816e7e822dbaaece8c5d4be14d (diff) | |
download | linux-fsl-qoriq-65b53e4cc90e59936733b3b95b9451d2ca47528d.tar.xz |
Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts:
drivers/net/tg3.c
drivers/net/wireless/rt2x00/rt2x00dev.c
net/mac80211/ieee80211_i.h
Diffstat (limited to 'Documentation/DocBook/kernel-locking.tmpl')
-rw-r--r-- | Documentation/DocBook/kernel-locking.tmpl | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 77c42f4..2510763 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> |