2015-06-11 15:37:50

by Nicholas Mc Guire

[permalink] [raw]
Subject: [PATCH] i2c: mv64xxx: remove unreachable signal case handling

'commit d295a86eab20 ("i2c: mv64xxx: work around signals causing I2C
transactions to be aborted")' removed the wait_event_interruptible_timeout
to prevent half/mixed i2c messages from being sent/received but forgot to
drop the signal received cases in the return handling. This just removes
this dead code and simplifies the error message as "time_left" only can be
0 here and thus it conveys no additional information.

Signed-off-by: Nicholas Mc Guire <[email protected]>
---

Patch was compile tested with multi_v7_defconfig
(implies CONFIG_I2C_MV64XXX=y)

Patch is against 4.1-rc7 (localversion-next is -next-20150611)

drivers/i2c/busses/i2c-mv64xxx.c | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 30059c1..a4f8ece 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -534,7 +534,6 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
{
long time_left;
unsigned long flags;
- char abort = 0;

time_left = wait_event_timeout(drv_data->waitq,
!drv_data->block, drv_data->adapter.timeout);
@@ -542,25 +541,17 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
spin_lock_irqsave(&drv_data->lock, flags);
if (!time_left) { /* Timed out */
drv_data->rc = -ETIMEDOUT;
- abort = 1;
- } else if (time_left < 0) { /* Interrupted/Error */
- drv_data->rc = time_left; /* errno value */
- abort = 1;
- }
-
- if (abort && drv_data->block) {
drv_data->aborting = 1;
spin_unlock_irqrestore(&drv_data->lock, flags);

time_left = wait_event_timeout(drv_data->waitq,
!drv_data->block, drv_data->adapter.timeout);

- if ((time_left <= 0) && drv_data->block) {
+ if (time_left == 0) {
drv_data->state = MV64XXX_I2C_STATE_IDLE;
dev_err(&drv_data->adapter.dev,
- "mv64xxx: I2C bus locked, block: %d, "
- "time_left: %d\n", drv_data->block,
- (int)time_left);
+ "mv64xxx: I2C bus locked, block: %d\n",
+ drv_data->block);
mv64xxx_i2c_hw_init(drv_data);
}
} else
--
1.7.10.4


2015-06-17 13:00:48

by Wolfram Sang

[permalink] [raw]
Subject: Re: [PATCH] i2c: mv64xxx: remove unreachable signal case handling

On Thu, Jun 11, 2015 at 05:27:33PM +0200, Nicholas Mc Guire wrote:
> 'commit d295a86eab20 ("i2c: mv64xxx: work around signals causing I2C
> transactions to be aborted")' removed the wait_event_interruptible_timeout
> to prevent half/mixed i2c messages from being sent/received but forgot to
> drop the signal received cases in the return handling. This just removes
> this dead code and simplifies the error message as "time_left" only can be
> 0 here and thus it conveys no additional information.
>
> Signed-off-by: Nicholas Mc Guire <[email protected]>
> ---
>
> Patch was compile tested with multi_v7_defconfig
> (implies CONFIG_I2C_MV64XXX=y)
>
> Patch is against 4.1-rc7 (localversion-next is -next-20150611)

Hmm, IMO this patch is too intrusive to be applied without actual
testing.

>
> drivers/i2c/busses/i2c-mv64xxx.c | 15 +++------------
> 1 file changed, 3 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
> index 30059c1..a4f8ece 100644
> --- a/drivers/i2c/busses/i2c-mv64xxx.c
> +++ b/drivers/i2c/busses/i2c-mv64xxx.c
> @@ -534,7 +534,6 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
> {
> long time_left;
> unsigned long flags;
> - char abort = 0;
>
> time_left = wait_event_timeout(drv_data->waitq,
> !drv_data->block, drv_data->adapter.timeout);
> @@ -542,25 +541,17 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
> spin_lock_irqsave(&drv_data->lock, flags);
> if (!time_left) { /* Timed out */
> drv_data->rc = -ETIMEDOUT;
> - abort = 1;
> - } else if (time_left < 0) { /* Interrupted/Error */
> - drv_data->rc = time_left; /* errno value */
> - abort = 1;
> - }
> -
> - if (abort && drv_data->block) {
> drv_data->aborting = 1;
> spin_unlock_irqrestore(&drv_data->lock, flags);
>
> time_left = wait_event_timeout(drv_data->waitq,
> !drv_data->block, drv_data->adapter.timeout);
>
> - if ((time_left <= 0) && drv_data->block) {

I am especially unsure about the drv_data->block removal. Did you double
check if we can do this?

> + if (time_left == 0) {
> drv_data->state = MV64XXX_I2C_STATE_IDLE;
> dev_err(&drv_data->adapter.dev,
> - "mv64xxx: I2C bus locked, block: %d, "
> - "time_left: %d\n", drv_data->block,
> - (int)time_left);
> + "mv64xxx: I2C bus locked, block: %d\n",
> + drv_data->block);

And if so, shouldn't that also be always 1 in the output here?

> mv64xxx_i2c_hw_init(drv_data);
> }
> } else

Maybe (not sure) it also helps to split the patch into everything
dealing with time_left as patch 1) and simplifying by drv_data->block
removal as patch2?

Thanks,

Wolfram


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2015-06-17 13:16:28

by Gregory CLEMENT

[permalink] [raw]
Subject: Re: [PATCH] i2c: mv64xxx: remove unreachable signal case handling

Hi Wolfram, Nicholas,

On 17/06/2015 15:00, Wolfram Sang wrote:
> On Thu, Jun 11, 2015 at 05:27:33PM +0200, Nicholas Mc Guire wrote:
>> 'commit d295a86eab20 ("i2c: mv64xxx: work around signals causing I2C
>> transactions to be aborted")' removed the wait_event_interruptible_timeout
>> to prevent half/mixed i2c messages from being sent/received but forgot to
>> drop the signal received cases in the return handling. This just removes
>> this dead code and simplifies the error message as "time_left" only can be
>> 0 here and thus it conveys no additional information.
>>
>> Signed-off-by: Nicholas Mc Guire <[email protected]>
>> ---
>>
>> Patch was compile tested with multi_v7_defconfig
>> (implies CONFIG_I2C_MV64XXX=y)
>>
>> Patch is against 4.1-rc7 (localversion-next is -next-20150611)
>
> Hmm, IMO this patch is too intrusive to be applied without actual
> testing.
>
>>
>> drivers/i2c/busses/i2c-mv64xxx.c | 15 +++------------
>> 1 file changed, 3 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
>> index 30059c1..a4f8ece 100644
>> --- a/drivers/i2c/busses/i2c-mv64xxx.c
>> +++ b/drivers/i2c/busses/i2c-mv64xxx.c
>> @@ -534,7 +534,6 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
>> {
>> long time_left;
>> unsigned long flags;
>> - char abort = 0;
>>
>> time_left = wait_event_timeout(drv_data->waitq,
>> !drv_data->block, drv_data->adapter.timeout);
>> @@ -542,25 +541,17 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
>> spin_lock_irqsave(&drv_data->lock, flags);
>> if (!time_left) { /* Timed out */
>> drv_data->rc = -ETIMEDOUT;
>> - abort = 1;
>> - } else if (time_left < 0) { /* Interrupted/Error */
>> - drv_data->rc = time_left; /* errno value */
>> - abort = 1;
>> - }
>> -
>> - if (abort && drv_data->block) {
>> drv_data->aborting = 1;
>> spin_unlock_irqrestore(&drv_data->lock, flags);
>>
>> time_left = wait_event_timeout(drv_data->waitq,
>> !drv_data->block, drv_data->adapter.timeout);
>>
>> - if ((time_left <= 0) && drv_data->block) {
>
> I am especially unsure about the drv_data->block removal. Did you double
> check if we can do this?
>
>> + if (time_left == 0) {
>> drv_data->state = MV64XXX_I2C_STATE_IDLE;
>> dev_err(&drv_data->adapter.dev,
>> - "mv64xxx: I2C bus locked, block: %d, "
>> - "time_left: %d\n", drv_data->block,
>> - (int)time_left);
>> + "mv64xxx: I2C bus locked, block: %d\n",
>> + drv_data->block);
>
> And if so, shouldn't that also be always 1 in the output here?
>
>> mv64xxx_i2c_hw_init(drv_data);
>> }
>> } else
>
> Maybe (not sure) it also helps to split the patch into everything
> dealing with time_left as patch 1) and simplifying by drv_data->block
> removal as patch2?

I agree. I would like to see 2 patches. The first one should be not controversial
and could be applied whereas the second one will need a deeper review.

Thanks,

Gregory



--
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

2015-06-17 13:49:50

by Nicholas Mc Guire

[permalink] [raw]
Subject: Re: [PATCH] i2c: mv64xxx: remove unreachable signal case handling

On Wed, 17 Jun 2015, Gregory CLEMENT wrote:

> Hi Wolfram, Nicholas,
>
> On 17/06/2015 15:00, Wolfram Sang wrote:
> > On Thu, Jun 11, 2015 at 05:27:33PM +0200, Nicholas Mc Guire wrote:
> >> 'commit d295a86eab20 ("i2c: mv64xxx: work around signals causing I2C
> >> transactions to be aborted")' removed the wait_event_interruptible_timeout
> >> to prevent half/mixed i2c messages from being sent/received but forgot to
> >> drop the signal received cases in the return handling. This just removes
> >> this dead code and simplifies the error message as "time_left" only can be
> >> 0 here and thus it conveys no additional information.
> >>
> >> Signed-off-by: Nicholas Mc Guire <[email protected]>
> >> ---
> >>
> >> Patch was compile tested with multi_v7_defconfig
> >> (implies CONFIG_I2C_MV64XXX=y)
> >>
> >> Patch is against 4.1-rc7 (localversion-next is -next-20150611)
> >
> > Hmm, IMO this patch is too intrusive to be applied without actual
> > testing.
> >
> >>
> >> drivers/i2c/busses/i2c-mv64xxx.c | 15 +++------------
> >> 1 file changed, 3 insertions(+), 12 deletions(-)
> >>
> >> diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
> >> index 30059c1..a4f8ece 100644
> >> --- a/drivers/i2c/busses/i2c-mv64xxx.c
> >> +++ b/drivers/i2c/busses/i2c-mv64xxx.c
> >> @@ -534,7 +534,6 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
> >> {
> >> long time_left;
> >> unsigned long flags;
> >> - char abort = 0;
> >>
> >> time_left = wait_event_timeout(drv_data->waitq,
> >> !drv_data->block, drv_data->adapter.timeout);
> >> @@ -542,25 +541,17 @@ mv64xxx_i2c_wait_for_completion(struct mv64xxx_i2c_data *drv_data)
> >> spin_lock_irqsave(&drv_data->lock, flags);
> >> if (!time_left) { /* Timed out */
> >> drv_data->rc = -ETIMEDOUT;
> >> - abort = 1;
> >> - } else if (time_left < 0) { /* Interrupted/Error */
> >> - drv_data->rc = time_left; /* errno value */
> >> - abort = 1;
> >> - }
> >> -
> >> - if (abort && drv_data->block) {
> >> drv_data->aborting = 1;
> >> spin_unlock_irqrestore(&drv_data->lock, flags);
> >>
> >> time_left = wait_event_timeout(drv_data->waitq,
> >> !drv_data->block, drv_data->adapter.timeout);
> >>
> >> - if ((time_left <= 0) && drv_data->block) {
> >
> > I am especially unsure about the drv_data->block removal. Did you double
> > check if we can do this?
> >

The consideration was
* wait_event_timeout was checkign !drv_data->block - so it it returned
the condition held OR timeout
* since it was a timeout here the condition was NOT met so either both
are true or both are wrong
I think the current logic only makes sense if one assumes that a signal case
is also possible.

> >> + if (time_left == 0) {
> >> drv_data->state = MV64XXX_I2C_STATE_IDLE;
> >> dev_err(&drv_data->adapter.dev,
> >> - "mv64xxx: I2C bus locked, block: %d, "
> >> - "time_left: %d\n", drv_data->block,
> >> - (int)time_left);
> >> + "mv64xxx: I2C bus locked, block: %d\n",
> >> + drv_data->block);
> >
> > And if so, shouldn't that also be always 1 in the output here?
> >

yes drv_data->block is 0 | 1 only - so that probably could be dropped
as well

> >> mv64xxx_i2c_hw_init(drv_data);
> >> }
> >> } else
> >
> > Maybe (not sure) it also helps to split the patch into everything
> > dealing with time_left as patch 1) and simplifying by drv_data->block
> > removal as patch2?
>
> I agree. I would like to see 2 patches. The first one should be not controversial
> and could be applied whereas the second one will need a deeper review.
>
thanks - will refactor and split it into two parts
and see if I can get this tested somehow - no urgency
as its really only cleanup.

thx!
hofrat