ChangeSet 1.2014.1.2, 2004/10/22 12:52:13-07:00, ebs@ebshome.net [PATCH] I2C: fix recently introduced race in IBM PPC4xx I2C driver On Tue, Oct 19, 2004 at 10:21:08PM -0700, Eugene Surovegin wrote: [snip] > It looks like this change added race I tried to avoid here. > > This code is modeled after __wait_event_interruptible_timeout, where > "prepare_to_wait" is done _before_ checking completion status. This > change breaks this, e.g. if IRQ happens right after we check iic->sts, > but before calling msleep_interruptible(). In this case we'll sleep > much more than required (seconds instead of microseconds) > > Greg, if my analysis is correct, please rollback this change. > > Nishanth, I'd be nice if you CC'ed me with this patch, my e-mail is at > the top of that source file. Oh, well. I should have used wait_event_interruptible_timeout when I ported this driver to 2.6. This patch fixes recently introduced race and also cleans ups some 2.4-ism. Signed-off-by: Eugene Surovegin Signed-off-by: Greg Kroah-Hartman drivers/i2c/busses/i2c-ibm_iic.c | 16 +++++----------- 1 files changed, 5 insertions(+), 11 deletions(-) diff -Nru a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c --- a/drivers/i2c/busses/i2c-ibm_iic.c 2004-11-08 18:56:20 -08:00 +++ b/drivers/i2c/busses/i2c-ibm_iic.c 2004-11-08 18:56:20 -08:00 @@ -412,18 +412,12 @@ if (dev->irq >= 0){ /* Interrupt mode */ - wait_queue_t wait; - init_waitqueue_entry(&wait, current); - - add_wait_queue(&dev->wq, &wait); - if (in_8(&iic->sts) & STS_PT) - msleep_interruptible(dev->adap.timeout * 1000); - remove_wait_queue(&dev->wq, &wait); - - if (unlikely(signal_pending(current))){ + ret = wait_event_interruptible_timeout(dev->wq, + !(in_8(&iic->sts) & STS_PT), dev->adap.timeout * HZ); + + if (unlikely(ret < 0)) DBG("%d: wait interrupted\n", dev->idx); - ret = -ERESTARTSYS; - } else if (unlikely(in_8(&iic->sts) & STS_PT)){ + else if (unlikely(in_8(&iic->sts) & STS_PT)){ DBG("%d: wait timeout\n", dev->idx); ret = -ETIMEDOUT; }