The following commit has been merged into the sched/psi branch of tip: Commit-ID: 61742a7cd5b194d2cc52d78de8ec6967634a4cd6 Gitweb: https://git.kernel.org/tip/61742a7cd5b194d2cc52d78de8ec6967634a4cd6 Author: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> AuthorDate: Wed, 20 Jul 2022 23:26:36 +02:00 Committer: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> CommitterDate: Thu, 01 Sep 2022 18:17:14 +02:00 devres: Slightly optimize alloc_dr() If the gfp flag used for the memory allocation already has __GFP_ZERO, then there is no need to explicitly clear the "struct devres_node". It is already zeroed. This saves a few cycles when using devm_zalloc() and co. In the case of devres_alloc() (which calls __devres_alloc_node()), the compiler could remove the test and the memset() because it should be able to see that the __GFP_ZERO flag is set. So this would make the code both faster and smaller. Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx> Link: https://lore.kernel.org/r/d255bd871484e63cdd628e819f929e2df59afb02.1658352383.git.christophe.jaillet@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/base/devres.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/base/devres.c b/drivers/base/devres.c index 864d0b3..4ab2b50 100644 --- a/drivers/base/devres.c +++ b/drivers/base/devres.c @@ -117,7 +117,9 @@ static __always_inline struct devres * alloc_dr(dr_release_t release, if (unlikely(!dr)) return NULL; - memset(dr, 0, offsetof(struct devres, data)); + /* No need to clear memory twice */ + if (!(gfp & __GFP_ZERO)) + memset(dr, 0, offsetof(struct devres, data)); INIT_LIST_HEAD(&dr->node.entry); dr->node.release = release;
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