Add a new if_not_cond_guard() macro to cleanup.h for handling
conditional guards such as mutext_trylock().
This is more ergonomic than scoped_cond_guard() for most use cases.
Instead of hiding the error handling statement in the macro args, it
works like a normal if statement and allow the error path to be indented
while the normal code flow path is not indented. And it avoid unwanted
side-effect from hidden for loop in scoped_cond_guard().
Signed-off-by: David Lechner <dlechner@baylibre.com>
---
include/linux/cleanup.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index 038b2d523bf8..682bb3fadfc9 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -273,6 +273,10 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
* an anonymous instance of the (guard) class, not recommended for
* conditional locks.
*
+ * if_not_cond_guard(name, args...) { <error handling> }:
+ * convenience macro for conditional guards that calls the statement that
+ * follows only if the lock was not acquired (typically an error return).
+ *
* scoped_guard (name, args...) { }:
* similar to CLASS(name, scope)(args), except the variable (with the
* explicit name 'scope') is declard in a for-loop such that its scope is
@@ -304,6 +308,13 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
#define __guard_ptr(_name) class_##_name##_lock_ptr
+#define __if_not_cond_guard(_name, _id, args...) \
+ CLASS(_name, _id)(args); \
+ if (!__guard_ptr(_name)(&_id))
+
+#define if_not_cond_guard(_name, args...) \
+ __if_not_cond_guard(_name, __UNIQUE_ID(guard), args)
+
#define scoped_guard(_name, args...) \
for (CLASS(_name, scope)(args), \
*done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
--
2.43.0On Tue, Oct 01, 2024 at 05:30:18PM -0500, David Lechner wrote:
> Add a new if_not_cond_guard() macro to cleanup.h for handling
> conditional guards such as mutext_trylock().
>
> This is more ergonomic than scoped_cond_guard() for most use cases.
> Instead of hiding the error handling statement in the macro args, it
> works like a normal if statement and allow the error path to be indented
> while the normal code flow path is not indented. And it avoid unwanted
> side-effect from hidden for loop in scoped_cond_guard().
>
> Signed-off-by: David Lechner <dlechner@baylibre.com>
> ---
> include/linux/cleanup.h | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
> index 038b2d523bf8..682bb3fadfc9 100644
> --- a/include/linux/cleanup.h
> +++ b/include/linux/cleanup.h
> @@ -273,6 +273,10 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
> * an anonymous instance of the (guard) class, not recommended for
> * conditional locks.
> *
> + * if_not_cond_guard(name, args...) { <error handling> }:
> + * convenience macro for conditional guards that calls the statement that
> + * follows only if the lock was not acquired (typically an error return).
> + *
> * scoped_guard (name, args...) { }:
> * similar to CLASS(name, scope)(args), except the variable (with the
> * explicit name 'scope') is declard in a for-loop such that its scope is
> @@ -304,6 +308,13 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
>
> #define __guard_ptr(_name) class_##_name##_lock_ptr
>
> +#define __if_not_cond_guard(_name, _id, args...) \
> + CLASS(_name, _id)(args); \
> + if (!__guard_ptr(_name)(&_id))
> +
> +#define if_not_cond_guard(_name, args...) \
> + __if_not_cond_guard(_name, __UNIQUE_ID(guard), args)
> +
> #define scoped_guard(_name, args...) \
> for (CLASS(_name, scope)(args), \
> *done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
So if I stick this on top of:
https://lkml.kernel.org/r/20241011121535.28049-1-przemyslaw.kitszel@intel.com
then I can add the below:
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -277,6 +277,8 @@ static inline class_##_name##_t class_##
* convenience macro for conditional guards that calls the statement that
* follows only if the lock was not acquired (typically an error return).
*
+ * Only for conditional locks.
+ *
* scoped_guard (name, args...) { }:
* similar to CLASS(name, scope)(args), except the variable (with the
* explicit name 'scope') is declard in a for-loop such that its scope is
@@ -290,7 +292,6 @@ static inline class_##_name##_t class_##
* acquire fails.
*
* Only for conditional locks.
- *
*/
#define __DEFINE_CLASS_IS_CONDITIONAL(_name, _is_cond) \
@@ -342,6 +343,7 @@ _label: \
__UNIQUE_ID(label), args)
#define __if_not_guard(_name, _id, args...) \
+ BUILD_BUG_ON(!__is_cond_ptr(_name)); \
CLASS(_name, _id)(args); \
if (!__guard_ptr(_name)(&_id))
That make sense to people?
I've queued these two patches:
git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/core
But lacking if_not_guard() users, the robot isn't really going to give
me much feedback there, I suppose...
Peter Zijlstra wrote: > On Tue, Oct 01, 2024 at 05:30:18PM -0500, David Lechner wrote: > > Add a new if_not_cond_guard() macro to cleanup.h for handling > > conditional guards such as mutext_trylock(). > > > > This is more ergonomic than scoped_cond_guard() for most use cases. > > Instead of hiding the error handling statement in the macro args, it > > works like a normal if statement and allow the error path to be indented > > while the normal code flow path is not indented. And it avoid unwanted > > side-effect from hidden for loop in scoped_cond_guard(). > > > > Signed-off-by: David Lechner <dlechner@baylibre.com> > > --- > > include/linux/cleanup.h | 11 +++++++++++ > > 1 file changed, 11 insertions(+) > > [..] > I've queued these two patches: > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/core > > But lacking if_not_guard() users, the robot isn't really going to give > me much feedback there, I suppose... Looks good. If that branch is rebase-able it would be nice to add some credit tags to "cleanup: Add conditional guard helper": Co-developed-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com> Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com> David and I talked about that here: http://lore.kernel.org/f4cc471a-b602-48d8-8323-15efcd602814@baylibre.com Also feel free to add: Reviewed-by: Dan Williams <dan.j.williams@intel.com> Thanks, Peter!
On Fri, Oct 18, 2024 at 12:29:27PM -0700, Dan Williams wrote: > Peter Zijlstra wrote: > > On Tue, Oct 01, 2024 at 05:30:18PM -0500, David Lechner wrote: > > > Add a new if_not_cond_guard() macro to cleanup.h for handling > > > conditional guards such as mutext_trylock(). > > > > > > This is more ergonomic than scoped_cond_guard() for most use cases. > > > Instead of hiding the error handling statement in the macro args, it > > > works like a normal if statement and allow the error path to be indented > > > while the normal code flow path is not indented. And it avoid unwanted > > > side-effect from hidden for loop in scoped_cond_guard(). > > > > > > Signed-off-by: David Lechner <dlechner@baylibre.com> > > > --- > > > include/linux/cleanup.h | 11 +++++++++++ > > > 1 file changed, 11 insertions(+) > > > > [..] > > I've queued these two patches: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/core > > > > But lacking if_not_guard() users, the robot isn't really going to give > > me much feedback there, I suppose... > > Looks good. If that branch is rebase-able it would be nice to add some > credit tags to "cleanup: Add conditional guard helper": > > Co-developed-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com> > Signed-off-by: Fabio M. De Francesco <fabio.m.de.francesco@linux.intel.com> > > David and I talked about that here: > > http://lore.kernel.org/f4cc471a-b602-48d8-8323-15efcd602814@baylibre.com > > Also feel free to add: > > Reviewed-by: Dan Williams <dan.j.williams@intel.com> I rebased because I had to magic in the v4 from Przemek, and I added the above tags to the if_not_guard() thing. I've also pushed out a locking/test branch that includes the iio conversion for the robots. Once I push to tip/locking/core (people will get robot mail) the commits should be stable and can be used in other branches if so desired.
On 10/18/24 13:15, Peter Zijlstra wrote:
> On Tue, Oct 01, 2024 at 05:30:18PM -0500, David Lechner wrote:
>> Add a new if_not_cond_guard() macro to cleanup.h for handling
>> conditional guards such as mutext_trylock().
>>
>> This is more ergonomic than scoped_cond_guard() for most use cases.
>> Instead of hiding the error handling statement in the macro args, it
>> works like a normal if statement and allow the error path to be indented
>> while the normal code flow path is not indented. And it avoid unwanted
>> side-effect from hidden for loop in scoped_cond_guard().
>>
>> Signed-off-by: David Lechner <dlechner@baylibre.com>
So this is guard()() with error handler for cond class of locks.
I would name such guard_or_err(), or guard_or_err_block(), to make it
obvious why there is a block attached (so bad we could not ENFORCE that
there is a block atached).
Then, having it, it would make sense to not only limit guard_or_err() to
cond class of locks, but also forbid plain guard() with cond locks
(instead just discouraging it in the doc).
>> ---
>> include/linux/cleanup.h | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
>> index 038b2d523bf8..682bb3fadfc9 100644
>> --- a/include/linux/cleanup.h
>> +++ b/include/linux/cleanup.h
>> @@ -273,6 +273,10 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
>> * an anonymous instance of the (guard) class, not recommended for
>> * conditional locks.
>> *
>> + * if_not_cond_guard(name, args...) { <error handling> }:
>> + * convenience macro for conditional guards that calls the statement that
>> + * follows only if the lock was not acquired (typically an error return).
>> + *
>> * scoped_guard (name, args...) { }:
>> * similar to CLASS(name, scope)(args), except the variable (with the
>> * explicit name 'scope') is declard in a for-loop such that its scope is
>> @@ -304,6 +308,13 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
>>
>> #define __guard_ptr(_name) class_##_name##_lock_ptr
>>
>> +#define __if_not_cond_guard(_name, _id, args...) \
>> + CLASS(_name, _id)(args); \
>> + if (!__guard_ptr(_name)(&_id))
>> +
>> +#define if_not_cond_guard(_name, args...) \
>> + __if_not_cond_guard(_name, __UNIQUE_ID(guard), args)
>> +
>> #define scoped_guard(_name, args...) \
>> for (CLASS(_name, scope)(args), \
>> *done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
>
>
> So if I stick this on top of:
>
> https://lkml.kernel.org/r/20241011121535.28049-1-przemyslaw.kitszel@intel.com
I have v4 that fixes non-cond version. Apologies it took me that long.
[v4]
https://lore.kernel.org/netdev/20241018113823.171256-1-przemyslaw.kitszel@intel.com
I have tested it also with the unrechable() calls removed, as suggested
by David Lechner here:
https://lore.kernel.org/netdev/0f4786e9-d738-435d-afb9-8c0c4a028ddb@baylibre.com
>
> then I can add the below:
>
> --- a/include/linux/cleanup.h
> +++ b/include/linux/cleanup.h
> @@ -277,6 +277,8 @@ static inline class_##_name##_t class_##
> * convenience macro for conditional guards that calls the statement that
> * follows only if the lock was not acquired (typically an error return).
> *
> + * Only for conditional locks.
> + *
> * scoped_guard (name, args...) { }:
> * similar to CLASS(name, scope)(args), except the variable (with the
> * explicit name 'scope') is declard in a for-loop such that its scope is
> @@ -290,7 +292,6 @@ static inline class_##_name##_t class_##
> * acquire fails.
> *
> * Only for conditional locks.
> - *
> */
>
> #define __DEFINE_CLASS_IS_CONDITIONAL(_name, _is_cond) \
> @@ -342,6 +343,7 @@ _label: \
> __UNIQUE_ID(label), args)
>
> #define __if_not_guard(_name, _id, args...) \
> + BUILD_BUG_ON(!__is_cond_ptr(_name)); \
> CLASS(_name, _id)(args); \
> if (!__guard_ptr(_name)(&_id))
>
>
> That make sense to people?
despite name, looks promising!
>
> I've queued these two patches:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/core
>
> But lacking if_not_guard() users, the robot isn't really going to give
> me much feedback there, I suppose...
Couldn't you just pick the other patches, that use the newly introduced
macro?
On Fri, 18 Oct 2024 14:31:43 +0200
Przemek Kitszel <przemyslaw.kitszel@intel.com> wrote:
> On 10/18/24 13:15, Peter Zijlstra wrote:
> > On Tue, Oct 01, 2024 at 05:30:18PM -0500, David Lechner wrote:
> >> Add a new if_not_cond_guard() macro to cleanup.h for handling
> >> conditional guards such as mutext_trylock().
> >>
> >> This is more ergonomic than scoped_cond_guard() for most use cases.
> >> Instead of hiding the error handling statement in the macro args, it
> >> works like a normal if statement and allow the error path to be indented
> >> while the normal code flow path is not indented. And it avoid unwanted
> >> side-effect from hidden for loop in scoped_cond_guard().
> >>
> >> Signed-off-by: David Lechner <dlechner@baylibre.com>
>
> So this is guard()() with error handler for cond class of locks.
> I would name such guard_or_err(), or guard_or_err_block(), to make it
> obvious why there is a block attached (so bad we could not ENFORCE that
> there is a block atached).
>
> Then, having it, it would make sense to not only limit guard_or_err() to
> cond class of locks, but also forbid plain guard() with cond locks
> (instead just discouraging it in the doc).
>
> >> ---
> >> include/linux/cleanup.h | 11 +++++++++++
> >> 1 file changed, 11 insertions(+)
> >>
> >> diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
> >> index 038b2d523bf8..682bb3fadfc9 100644
> >> --- a/include/linux/cleanup.h
> >> +++ b/include/linux/cleanup.h
> >> @@ -273,6 +273,10 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
> >> * an anonymous instance of the (guard) class, not recommended for
> >> * conditional locks.
> >> *
> >> + * if_not_cond_guard(name, args...) { <error handling> }:
> >> + * convenience macro for conditional guards that calls the statement that
> >> + * follows only if the lock was not acquired (typically an error return).
> >> + *
> >> * scoped_guard (name, args...) { }:
> >> * similar to CLASS(name, scope)(args), except the variable (with the
> >> * explicit name 'scope') is declard in a for-loop such that its scope is
> >> @@ -304,6 +308,13 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
> >>
> >> #define __guard_ptr(_name) class_##_name##_lock_ptr
> >>
> >> +#define __if_not_cond_guard(_name, _id, args...) \
> >> + CLASS(_name, _id)(args); \
> >> + if (!__guard_ptr(_name)(&_id))
> >> +
> >> +#define if_not_cond_guard(_name, args...) \
> >> + __if_not_cond_guard(_name, __UNIQUE_ID(guard), args)
> >> +
> >> #define scoped_guard(_name, args...) \
> >> for (CLASS(_name, scope)(args), \
> >> *done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
> >
> >
> > So if I stick this on top of:
> >
> > https://lkml.kernel.org/r/20241011121535.28049-1-przemyslaw.kitszel@intel.com
>
> I have v4 that fixes non-cond version. Apologies it took me that long.
> [v4]
> https://lore.kernel.org/netdev/20241018113823.171256-1-przemyslaw.kitszel@intel.com
>
> I have tested it also with the unrechable() calls removed, as suggested
> by David Lechner here:
> https://lore.kernel.org/netdev/0f4786e9-d738-435d-afb9-8c0c4a028ddb@baylibre.com
>
> >
> > then I can add the below:
> >
> > --- a/include/linux/cleanup.h
> > +++ b/include/linux/cleanup.h
> > @@ -277,6 +277,8 @@ static inline class_##_name##_t class_##
> > * convenience macro for conditional guards that calls the statement that
> > * follows only if the lock was not acquired (typically an error return).
> > *
> > + * Only for conditional locks.
> > + *
> > * scoped_guard (name, args...) { }:
> > * similar to CLASS(name, scope)(args), except the variable (with the
> > * explicit name 'scope') is declard in a for-loop such that its scope is
> > @@ -290,7 +292,6 @@ static inline class_##_name##_t class_##
> > * acquire fails.
> > *
> > * Only for conditional locks.
> > - *
> > */
> >
> > #define __DEFINE_CLASS_IS_CONDITIONAL(_name, _is_cond) \
> > @@ -342,6 +343,7 @@ _label: \
> > __UNIQUE_ID(label), args)
> >
> > #define __if_not_guard(_name, _id, args...) \
> > + BUILD_BUG_ON(!__is_cond_ptr(_name)); \
> > CLASS(_name, _id)(args); \
> > if (!__guard_ptr(_name)(&_id))
> >
> >
> > That make sense to people?
>
> despite name, looks promising!
>
> >
> > I've queued these two patches:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/core
> >
> > But lacking if_not_guard() users, the robot isn't really going to give
> > me much feedback there, I suppose...
>
> Couldn't you just pick the other patches, that use the newly introduced
> macro?
For a test, sure, but there is a lot of ad7380 work in flight and I'd rather
not push that back a cycle for this improvement (nice though it is!)
If it looks good, an immutable branch would be great, or I could just merge
from Peter's tree if that is stable.
Similarly there is a high risk of the CXL code changing for other reasons
this cycle, but same solution would work.
Jonathan
>
>
>
[ add Fabio ] David Lechner wrote: > Add a new if_not_cond_guard() macro to cleanup.h for handling > conditional guards such as mutext_trylock(). > > This is more ergonomic than scoped_cond_guard() for most use cases. > Instead of hiding the error handling statement in the macro args, it > works like a normal if statement and allow the error path to be indented > while the normal code flow path is not indented. And it avoid unwanted > side-effect from hidden for loop in scoped_cond_guard(). > > Signed-off-by: David Lechner <dlechner@baylibre.com> Hi David, When you update this to the if_not_guard() name can you also add Fabio as a co-developer? His work [1] contributed to eliciting the response from Linus, and then this patch takes the novel additional step to create an "if ()" macro. Thanks for pushing this forward! [1]: http://lore.kernel.org/20240130164059.25130-1-fabio.maria.de.francesco@linux.intel.com
On 10/4/24 12:34 PM, Dan Williams wrote: > [ add Fabio ] > > David Lechner wrote: >> Add a new if_not_cond_guard() macro to cleanup.h for handling >> conditional guards such as mutext_trylock(). >> >> This is more ergonomic than scoped_cond_guard() for most use cases. >> Instead of hiding the error handling statement in the macro args, it >> works like a normal if statement and allow the error path to be indented >> while the normal code flow path is not indented. And it avoid unwanted >> side-effect from hidden for loop in scoped_cond_guard(). >> >> Signed-off-by: David Lechner <dlechner@baylibre.com> > > Hi David, > > When you update this to the if_not_guard() name can you also add Fabio as a > co-developer? His work [1] contributed to eliciting the response from Linus, > and then this patch takes the novel additional step to create an "if ()" macro. > > Thanks for pushing this forward! > > [1]: http://lore.kernel.org/20240130164059.25130-1-fabio.maria.de.francesco@linux.intel.com Sure, I didn't dig deep enough to find that patch, but basically the same idea. :-)
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