On Thu, Jan 04, 2024 at 09:17:08AM +0100, Benjamin Bara wrote:
From: Benjamin Bara benjamin.bara@skidata.com
Since commit aa49c90894d0 ("i2c: core: Run atomic i2c xfer when !preemptible"), the whole reboot/power off sequence on non-preempt kernels is using atomic i2c xfer, as !preemptible() always results to 1.
During device_shutdown(), the i2c might be used a lot and not all busses have implemented an atomic xfer handler. This results in a lot of avoidable noise, like:
[ 12.687169] No atomic I2C transfer handler for 'i2c-0' [ 12.692313] WARNING: CPU: 6 PID: 275 at drivers/i2c/i2c-core.h:40 i2c_smbus_xfer+0x100/0x118 ...
Fix this by allowing non-atomic xfer when the interrupts are enabled, as it was before.
Fixes: aa49c90894d0 ("i2c: core: Run atomic i2c xfer when !preemptible") Cc: stable@vger.kernel.org # v5.2+ Signed-off-by: Benjamin Bara benjamin.bara@skidata.com
Thanks! The code looks what I also would have suggested reading the bug reports. So:
Applied to for-current, thanks!
- /*
* non-atomic xfers often use wait_for_completion*() calls to wait* efficiently (schedule out voluntarily) on the completion of the xfer,* which are then "completed" by an IRQ. If the constraints are not* satisfied, fall back to an atomic xfer.*/- return system_state > SYSTEM_RUNNING &&
(IS_ENABLED(CONFIG_PREEMPT_COUNT) ? !preemptible() : irqs_disabled());
I removed the comment, though. I don't think it explains the following code well enough, i.e. why we have a decision based on a Kconfig symbol. We can (and should) fix this incrementally, though. I hope this is OK with everyone.
Thanks to everyone putting work into this. Much appreciated!