On Fri, 07 Nov 2008 17:05:35 +0100 Krzysztof Halasa <[EMAIL PROTECTED]> wrote:
> Jean Delvare <[EMAIL PROTECTED]> writes: > > > The situation is far from perfect though. For one thing, I seem to > > recall that Andrew Morton didn't like the approach taken in > > i2c_transfer(). For another, i2c_smbus_xfer() was not yet modified so > > at this point only I2C-level transactions can be non-sleeping, > > SMBus-level transactions can't. But all this could be fixed by anyone > > who cares about these specific issues. > > Thanks, I'll look at it. The problem (well: bug) is that in_atomic() returns false inside a spinlock when CONFIG_PREEMPT=n. The code as it stands can sleep inside a spinlock, which is deadlockable if a scheduled-to task tries to take the same spinlock. There is no means like this by which a piece of code can determine whether it can call schedule(). The pattern which we use in many many places (most especially GFP_KERNEL/GFP_ATOMIC) is to pass a flag down to callees telling them in some manner which context they were called from. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
