Messages in this thread | | | Date | Tue, 9 Apr 2019 15:08:45 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 01/18] drivers core: Add I/O ASID allocator |
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On Tue, Apr 09, 2019 at 06:21:30PM +0300, Andriy Shevchenko wrote: > On Tue, Apr 09, 2019 at 07:53:08AM -0700, Paul E. McKenney wrote: > > On Tue, Apr 09, 2019 at 01:30:30PM +0300, Andriy Shevchenko wrote: > > > On Tue, Apr 09, 2019 at 03:04:36AM -0700, Christoph Hellwig wrote: > > > > On Tue, Apr 09, 2019 at 01:00:49PM +0300, Andriy Shevchenko wrote: > > > > > I think it makes sense to add a helper macro to rcupdate.h > > > > > (and we have several cases in kernel that can utilize it) > > > > > > > > > > #define kfree_non_null_rcu(ptr, rcu_head) \ > > > > > do { \ > > > > > if (ptr) \ > > > > > kfree_rcu(ptr, rcu_head); \ > > > > > } while (0) > > > > > > > > > > as a more common pattern for resource deallocators. > > > > > > > > I think that should move straight into kfree_rcu. > > > > > > Possible. I didn't dare to offer this due to lack of knowledge how it's used in > > > other places. > > > > > > > In general > > > > we expect *free* to deal with NULL pointers transparently, so we > > > > should do so here as well. > > > > > > Exactly my point, thanks. > > > > As shown below? > > Looks pretty much good to me, thanks! > Reviewed-by: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Applied, thank you!
Thanx, Paul
> > And now that you mention it, it is a bit surprising that no one has > > complained before. ;-) > > > > Thanx, Paul > > > > ------------------------------------------------------------------------ > > > > commit 23ad938244968e9d2a8001a1c52887c113b182f6 > > Author: Paul E. McKenney <paulmck@linux.ibm.com> > > Date: Tue Apr 9 07:48:18 2019 -0700 > > > > rcu: Make kfree_rcu() ignore NULL pointers > > > > This commit makes the kfree_rcu() macro's semantics be consistent > > with the likes of kfree() by adding a check for NULL pointers, so > > that kfree_rcu(NULL, ...) is a no-op. > > > > Reported-by: Andriy Shevchenko <andriy.shevchenko@linux.intel.com> > > Reported-by: Christoph Hellwig <hch@infradead.org> > > Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> > > > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > > index 922bb6848813..c68649b9bcec 100644 > > --- a/include/linux/rcupdate.h > > +++ b/include/linux/rcupdate.h > > @@ -828,9 +828,13 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) > > * The BUILD_BUG_ON check must not involve any function calls, hence the > > * checks are done in macros here. > > */ > > -#define kfree_rcu(ptr, rcu_head) \ > > - __kfree_rcu(&((ptr)->rcu_head), offsetof(typeof(*(ptr)), rcu_head)) > > - > > +#define kfree_rcu(ptr, rhf) \ > > +do { \ > > + typeof (ptr) ___p = (ptr); \ > > + \ > > + if (___p) \ > > + __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ > > +} while (0) > > > > /* > > * Place this after a lock-acquisition primitive to guarantee that > > > > -- > With Best Regards, > Andy Shevchenko > >
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