The init_completion() call does reinit not only the variable carrying
the flag that the completion finished, but also initialized the
waitqueue associated with the completion. On the contrary, the
INIT_COMPLETION() call only reinits the flag.
In case there was anything still stuck in the waitqueue, subsequent call
to init_completion() would be able to create possible race condition. This
patch uses the proper function and moves init_completion() into .probe() call
of the driver, to be issued only once.
Note that such scenario is impossible, since two threads can never enter the
mxs_i2c_xfer_msg(), since whole this section is protected by mutex in I2C core.
This by no means allows this issue to exit though.
Signed-off-by: Marek Vasut <marex@xxxxxxx>
Cc: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
Cc: Shawn Guo <shawn.guo@xxxxxxxxxx>
Cc: Wolfram Sang <w.sang@xxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-mxs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-mxs.c b/drivers/i2c/busses/i2c-mxs.c
index 6ed53da..47d5d53 100644
--- a/drivers/i2c/busses/i2c-mxs.c
+++ b/drivers/i2c/busses/i2c-mxs.c
@@ -316,7 +316,7 @@ static int mxs_i2c_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg,
if (msg->len == 0)
return -EINVAL;
- init_completion(&i2c->cmd_complete);
+ INIT_COMPLETION(i2c->cmd_complete);
i2c->cmd_err = 0;
ret = mxs_i2c_dma_setup_xfer(adap, msg, flags);
@@ -473,6 +473,8 @@ static int __devinit mxs_i2c_probe(struct platform_device *pdev)
i2c->dev = dev;
i2c->speed = &mxs_i2c_95kHz_config;
+ init_completion(&i2c->cmd_complete);
+
if (dev->of_node) {
err = mxs_i2c_get_ofdata(i2c);
if (err)
--
1.7.10.4
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