| Message ID | 1573873650-62511-1-git-send-email-chenwandun@huawei.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | powerpc/pseries: remove variable 'status' set but not used | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch powerpc/merge (3b4852888d3f7e0cde65b29af9c518f4019e145f) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 32 lines checked |
| snowpatch_ozlabs/needsstable | success | Patch has no Fixes tags |
Chen Wandun <chenwandun@huawei.com> writes: > Fixes gcc '-Wunused-but-set-variable' warning: > > arch/powerpc/platforms/pseries/ras.c: In function ras_epow_interrupt: > arch/powerpc/platforms/pseries/ras.c:319:6: warning: variable status set but not used [-Wunused-but-set-variable] Thanks for the patch. But it almost certainly is wrong to not check the status. It's calling firmware and just assuming that the call succeeded. It then goes on to use the result that should have been written by firmware, but is now potentially random junk. So I'd much rather a patch to change it to check the status. > diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c > index 1d7f973..4a61d0f 100644 > --- a/arch/powerpc/platforms/pseries/ras.c > +++ b/arch/powerpc/platforms/pseries/ras.c > @@ -316,12 +316,11 @@ static irqreturn_t ras_hotplug_interrupt(int irq, void *dev_id) > /* Handle environmental and power warning (EPOW) interrupts. */ > static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) > { > - int status; > int state; > int critical; > > - status = rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, > - &state); > + rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, > + &state); This is calling a helper which already does some translation of the return value, any value < 0 indicates an error. > @@ -330,12 +329,12 @@ static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) > > spin_lock(&ras_log_buf_lock); > > - status = rtas_call(ras_check_exception_token, 6, 1, NULL, > - RTAS_VECTOR_EXTERNAL_INTERRUPT, > - virq_to_hw(irq), > - RTAS_EPOW_WARNING, > - critical, __pa(&ras_log_buf), > - rtas_get_error_log_max()); > + rtas_call(ras_check_exception_token, 6, 1, NULL, > + RTAS_VECTOR_EXTERNAL_INTERRUPT, > + virq_to_hw(irq), > + RTAS_EPOW_WARNING, > + critical, __pa(&ras_log_buf), > + rtas_get_error_log_max()); This is directly calling firmware. As documented in LoPAPR, a negative status indicates an error, 0 indicates a new error log was found (ie. the function should continue), or 1 there was no error log (ie. nothing to do). cheers > log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0); > > -- > 2.7.4
On 11/18/19 9:53 PM, Michael Ellerman wrote: > Chen Wandun <chenwandun@huawei.com> writes: >> Fixes gcc '-Wunused-but-set-variable' warning: >> >> arch/powerpc/platforms/pseries/ras.c: In function ras_epow_interrupt: >> arch/powerpc/platforms/pseries/ras.c:319:6: warning: variable status set but not used [-Wunused-but-set-variable] > > Thanks for the patch. > > But it almost certainly is wrong to not check the status. Agreed, I started drafting a NACK response, but got sidetracked. > > It's calling firmware and just assuming that the call succeeded. It then > goes on to use the result that should have been written by firmware, but > is now potentially random junk. > > So I'd much rather a patch to change it to check the status. +1 > >> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c >> index 1d7f973..4a61d0f 100644 >> --- a/arch/powerpc/platforms/pseries/ras.c >> +++ b/arch/powerpc/platforms/pseries/ras.c >> @@ -316,12 +316,11 @@ static irqreturn_t ras_hotplug_interrupt(int irq, void *dev_id) >> /* Handle environmental and power warning (EPOW) interrupts. */ >> static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) >> { >> - int status; >> int state; >> int critical; >> >> - status = rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, >> - &state); >> + rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, >> + &state); > > This is calling a helper which already does some translation of the > return value, any value < 0 indicates an error. There are three possible architected failures here: Hardware, Non-existant sensor, and an DR isolation error which namely would be reported in the status as -EIO, -EINVAL, and -EFAULT. Further, the EPOW sensor is required, and is not a DR entity so we can never get an -EINVAL or -EFAULT (baring broken firmware). This leaves -EIO (HARDWARE_ERROR) and as I mention further down this will generate its own error log in response. So, I don't think we need to do any reporting here, and just return. > >> @@ -330,12 +329,12 @@ static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) >> >> spin_lock(&ras_log_buf_lock); >> >> - status = rtas_call(ras_check_exception_token, 6, 1, NULL, >> - RTAS_VECTOR_EXTERNAL_INTERRUPT, >> - virq_to_hw(irq), >> - RTAS_EPOW_WARNING, >> - critical, __pa(&ras_log_buf), >> - rtas_get_error_log_max()); >> + rtas_call(ras_check_exception_token, 6, 1, NULL, >> + RTAS_VECTOR_EXTERNAL_INTERRUPT, >> + virq_to_hw(irq), >> + RTAS_EPOW_WARNING, >> + critical, __pa(&ras_log_buf), >> + rtas_get_error_log_max()); > > This is directly calling firmware. > > As documented in LoPAPR, a negative status indicates an error, 0 > indicates a new error log was found (ie. the function should continue), > or 1 there was no error log (ie. nothing to do). It is highly unlikely that we will find no new error log since we are processing an interrupt that supposedly fired to tell us there is a new one. However, the ras_log_buf is never zeroed so in the unlikely case there is no new error log we will parse stale data from the previous log. Better safe than sorry and just return. In the case of an error the only error code we supposedly can get here is -1 (HARDWARE_ERROR), and the RTAS handling will generate an error log in response to that. So, I don't think we need to report anything here. I would suggest for the (status != 0) case that you just return. -Tyrel > > cheers > >> log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0); >> >> -- >> 2.7.4
OK, I will make a modification and repost the patch. Thanks Chen Wandun On 2019/11/21 5:34, Tyrel Datwyler wrote: > On 11/18/19 9:53 PM, Michael Ellerman wrote: >> Chen Wandun <chenwandun@huawei.com> writes: >>> Fixes gcc '-Wunused-but-set-variable' warning: >>> >>> arch/powerpc/platforms/pseries/ras.c: In function ras_epow_interrupt: >>> arch/powerpc/platforms/pseries/ras.c:319:6: warning: variable status set but not used [-Wunused-but-set-variable] >> >> Thanks for the patch. >> >> But it almost certainly is wrong to not check the status. > > Agreed, I started drafting a NACK response, but got sidetracked. > >> >> It's calling firmware and just assuming that the call succeeded. It then >> goes on to use the result that should have been written by firmware, but >> is now potentially random junk. >> >> So I'd much rather a patch to change it to check the status. > > +1 > >> >>> diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c >>> index 1d7f973..4a61d0f 100644 >>> --- a/arch/powerpc/platforms/pseries/ras.c >>> +++ b/arch/powerpc/platforms/pseries/ras.c >>> @@ -316,12 +316,11 @@ static irqreturn_t ras_hotplug_interrupt(int irq, void *dev_id) >>> /* Handle environmental and power warning (EPOW) interrupts. */ >>> static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) >>> { >>> - int status; >>> int state; >>> int critical; >>> >>> - status = rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, >>> - &state); >>> + rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, >>> + &state); >> >> This is calling a helper which already does some translation of the >> return value, any value < 0 indicates an error. > > There are three possible architected failures here: Hardware, Non-existant > sensor, and an DR isolation error which namely would be reported in the status > as -EIO, -EINVAL, and -EFAULT. Further, the EPOW sensor is required, and is not > a DR entity so we can never get an -EINVAL or -EFAULT (baring broken firmware). > This leaves -EIO (HARDWARE_ERROR) and as I mention further down this will > generate its own error log in response. So, I don't think we need to do any > reporting here, and just return. > >> >>> @@ -330,12 +329,12 @@ static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) >>> >>> spin_lock(&ras_log_buf_lock); >>> >>> - status = rtas_call(ras_check_exception_token, 6, 1, NULL, >>> - RTAS_VECTOR_EXTERNAL_INTERRUPT, >>> - virq_to_hw(irq), >>> - RTAS_EPOW_WARNING, >>> - critical, __pa(&ras_log_buf), >>> - rtas_get_error_log_max()); >>> + rtas_call(ras_check_exception_token, 6, 1, NULL, >>> + RTAS_VECTOR_EXTERNAL_INTERRUPT, >>> + virq_to_hw(irq), >>> + RTAS_EPOW_WARNING, >>> + critical, __pa(&ras_log_buf), >>> + rtas_get_error_log_max()); >> >> This is directly calling firmware. >> >> As documented in LoPAPR, a negative status indicates an error, 0 >> indicates a new error log was found (ie. the function should continue), >> or 1 there was no error log (ie. nothing to do). > > It is highly unlikely that we will find no new error log since we are processing > an interrupt that supposedly fired to tell us there is a new one. However, the > ras_log_buf is never zeroed so in the unlikely case there is no new error log we > will parse stale data from the previous log. Better safe than sorry and just return. > > In the case of an error the only error code we supposedly can get here is -1 > (HARDWARE_ERROR), and the RTAS handling will generate an error log in response > to that. So, I don't think we need to report anything here. I would suggest for > the (status != 0) case that you just return. > > -Tyrel > >> >> cheers >> >>> log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0); >>> >>> -- >>> 2.7.4 > > > . >
diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c index 1d7f973..4a61d0f 100644 --- a/arch/powerpc/platforms/pseries/ras.c +++ b/arch/powerpc/platforms/pseries/ras.c @@ -316,12 +316,11 @@ static irqreturn_t ras_hotplug_interrupt(int irq, void *dev_id) /* Handle environmental and power warning (EPOW) interrupts. */ static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) { - int status; int state; int critical; - status = rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, - &state); + rtas_get_sensor_fast(EPOW_SENSOR_TOKEN, EPOW_SENSOR_INDEX, + &state); if (state > 3) critical = 1; /* Time Critical */ @@ -330,12 +329,12 @@ static irqreturn_t ras_epow_interrupt(int irq, void *dev_id) spin_lock(&ras_log_buf_lock); - status = rtas_call(ras_check_exception_token, 6, 1, NULL, - RTAS_VECTOR_EXTERNAL_INTERRUPT, - virq_to_hw(irq), - RTAS_EPOW_WARNING, - critical, __pa(&ras_log_buf), - rtas_get_error_log_max()); + rtas_call(ras_check_exception_token, 6, 1, NULL, + RTAS_VECTOR_EXTERNAL_INTERRUPT, + virq_to_hw(irq), + RTAS_EPOW_WARNING, + critical, __pa(&ras_log_buf), + rtas_get_error_log_max()); log_error(ras_log_buf, ERR_TYPE_RTAS_LOG, 0);
Fixes gcc '-Wunused-but-set-variable' warning: arch/powerpc/platforms/pseries/ras.c: In function ras_epow_interrupt: arch/powerpc/platforms/pseries/ras.c:319:6: warning: variable status set but not used [-Wunused-but-set-variable] Signed-off-by: Chen Wandun <chenwandun@huawei.com> --- arch/powerpc/platforms/pseries/ras.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-)