| Message ID | 20230327-tegra-pmic-reboot-v6-2-af44a4cd82e9@skidata.com |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | mfd: tps6586x: register restart handler | expand |
On 5/9/23 22:03, Benjamin Bara wrote: > From: Benjamin Bara <benjamin.bara@skidata.com> > > Since bae1d3a05a8b, 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: bae1d3a05a8b ("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> > Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com> > --- > drivers/i2c/i2c-core.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h > index 1247e6e6e975..05b8b8dfa9bd 100644 > --- a/drivers/i2c/i2c-core.h > +++ b/drivers/i2c/i2c-core.h > @@ -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) > Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
On 21:03-20230509, Benjamin Bara wrote: > From: Benjamin Bara <benjamin.bara@skidata.com> > > Since bae1d3a05a8b, 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: bae1d3a05a8b ("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> > Signed-off-by: Benjamin Bara <benjamin.bara@skidata.com> > --- > drivers/i2c/i2c-core.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h > index 1247e6e6e975..05b8b8dfa9bd 100644 > --- a/drivers/i2c/i2c-core.h > +++ b/drivers/i2c/i2c-core.h > @@ -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) > > -- > 2.34.1 > Tested-by: Nishanth Menon <nm@ti.com> This in addition to a deeper bug in our driver seems to have helped resolve a report we had been looking at. Tested on beagleplay platform https://lore.kernel.org/all/ZGeHMjlnob2GFyHF@francesco-nb.int.toradex.com/
diff --git a/drivers/i2c/i2c-core.h b/drivers/i2c/i2c-core.h index 1247e6e6e975..05b8b8dfa9bd 100644 --- a/drivers/i2c/i2c-core.h +++ b/drivers/i2c/i2c-core.h @@ -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)