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| author | Vincent Palatin <vpalatin@chromium.org> | 2012-03-14 20:58:52 +0000 |
|---|---|---|
| committer | Vincent Palatin <vpalatin@chromium.org> | 2012-03-14 20:58:52 +0000 |
| commit | ce60b937cb172690222b19026212718aac6fd469 (patch) | |
| tree | 5ea5c163fab135725cd140520395a64353e0acdc | |
| parent | 1a3becdbc2b99e9b215d8b21dba95f85b1469def (diff) | |
| download | chrome-ec-ce60b937cb172690222b19026212718aac6fd469.tar.gz | |
mutex: retry immediatly if we could not get exclusive access
When updating the lock field of the mutex to acquire it, if the store
exclusive fails, we want to retry immediatly else if the failure has
been triggered by the other user doing the mutex_unlock we might not be
woken up.
Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
BUG=chrome-os-partner:8492
TEST=run on proto-0.5 and see that the temperature sensor and battery
tasks are longer hanging (see the bug for details how to check it)
Change-Id: I0c8a4e997666a7781b3837f0dbbc47ffbc06b6c3
| -rw-r--r-- | core/cortex-m/task.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/core/cortex-m/task.c b/core/cortex-m/task.c index aed0a6b13c..4e4928929e 100644 --- a/core/cortex-m/task.c +++ b/core/cortex-m/task.c @@ -339,8 +339,11 @@ void mutex_lock(struct mutex *mtx) " it eq\n" " strexeq %0, %2, [%1]\n" : "=&r" (value) - : "r" (&mtx->lock), "r" (1) : "cc"); - if (value) { + : "r" (&mtx->lock), "r" (2) : "cc"); + /* "value" is equals to 1 if the store conditional failed, + * 2 if somebody else owns the mutex, 0 else. + */ + if (value == 2) { /* contention on the mutex */ task_wait_msg(0); } |