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 --- Hi!
As there are a couple of bug reports already about missing atomic i2c xfer handler warnings on non-preemptive configs around [1], this is an attempt to reduce the avoidable noise.
thanks & regards Benjamin
[1] https://lore.kernel.org/all/20230327-tegra-pmic-reboot-v7-2-18699d5dcd76@ski... --- drivers/i2c/i2c-core.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h index 05b8b8dfa9bd..e48c0cd21438 100644 --- a/drivers/i2c/i2c-core.h +++ b/drivers/i2c/i2c-core.h @@ -3,6 +3,7 @@ * i2c-core.h - interfaces internal to the I2C framework */
+#include <linux/kconfig.h> #include <linux/rwsem.h>
struct i2c_devinfo { @@ -29,7 +30,14 @@ int i2c_dev_irq_from_resources(const struct resource *resources, */ static inline bool i2c_in_atomic_xfer_mode(void) { - return system_state > SYSTEM_RUNNING && !preemptible(); + /* + * 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()); }
static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap)
--- base-commit: 610a9b8f49fbcf1100716370d3b5f6f884a2835a change-id: 20240104-i2c-atomic-2435f835b598
Best regards,
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
Tested-by: Michael Walle mwalle@kernel.org
Thanks for the fix, if there will be a -rc9 this should definitely go in.
-michael
On 1/4/24 09:17, 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
On x86_64 and 6.7-rc8 with voluntary preemption:
Tested-by: Tor Vic torvic9@mailbox.org
Thanks for the fix!
Best regards,
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!
Thanks a lot for this patch! It fixed big backtrace I saw at very last stage of reboot. That backtrace occupied whole FullHD screen. Now it is gone. Thanks! My computer is laptop Dell Inspiron.
I hope this patch will soon arrive to debian buster lts
Askar Safin
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
linux-stable-mirror@lists.linaro.org
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Askar Safin -
Benjamin Bara -
Michael Walle -
Tor Vic -
Wolfram Sang