GuillaumeHemmen/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2024-11-01 13:03:25 +01:00
Code Issues Projects Releases Packages Wiki Activity

i2c: core: Run atomic i2c xfer when !preemptible

Browse source 
Since bae1d3a05a, i2c transfers are non-atomic if preemption is
disabled. However, non-atomic i2c transfers require preemption (e.g. in
wait_for_completion() while waiting for the DMA).

panic() calls preempt_disable_notrace() before calling
emergency_restart(). Therefore, if an i2c device is used for the
restart, the xfer should be atomic. This avoids warnings like:

[   12.667612] WARNING: CPU: 1 PID: 1 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0x33c/0x6b0
[   12.676926] Voluntary context switch within RCU read-side critical section!
...
[   12.742376]  schedule_timeout from wait_for_completion_timeout+0x90/0x114
[   12.749179]  wait_for_completion_timeout from tegra_i2c_wait_completion+0x40/0x70
...
[   12.994527]  atomic_notifier_call_chain from machine_restart+0x34/0x58
[   13.001050]  machine_restart from panic+0x2a8/0x32c

Use !preemptible() instead, which is basically the same check as
pre-v5.2.

Fixes: bae1d3a05a ("i2c: core: remove use of in_atomic()")
Cc: stable@vger.kernel.org # v5.2+
Suggested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Acked-by: Wolfram Sang <wsa@kernel.org>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com>
Link: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v7-2-18699d5dcd76@skidata.com
Signed-off-by: Lee Jones <lee@kernel.org>
This commit is contained in:
Benjamin Bara 2023-07-15 09:53:24 +02:00 committed by Lee Jones
parent 60466c0679
commit aa49c90894
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
drivers/i2c/i2c-core.h
View file

@ -29,7 +29,7 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
*/
static inline bool i2c_in_atomic_xfer_mode(void)
{
return system_state > SYSTEM_RUNNING && irqs_disabled();
return system_state > SYSTEM_RUNNING && !preemptible();
}
static inline int __i2c_lock_bus_helper(struct i2c_adapter *adap)