diff options
| author |   Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2025-05-12 11:27:36 +0200 |
|---|---|---|
| committer |   Paolo Abeni <pabeni@redhat.com> | 2025-05-15 15:23:31 +0200 |
| commit | c50d295c37f2648a8d9e8a572fedaad027d134bb (patch) | |
| tree | f005631be8e0e712a6b81180ad9b35b02f4f7896 | |
| parent | rds: Acquire per-CPU pointer within BH disabled section (diff) | |
| download | wireguard-linux-c50d295c37f2648a8d9e8a572fedaad027d134bb.tar.xz wireguard-linux-c50d295c37f2648a8d9e8a572fedaad027d134bb.zip | |
rds: Use nested-BH locking for rds_page_remainder
rds_page_remainder is a per-CPU variable and relies on disabled BH for its
locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT
this data structure requires explicit locking.
Add a local_lock_t to the data structure and use
local_lock_nested_bh() for locking. This change adds only lockdep
coverage and does not alter the functional behaviour for !PREEMPT_RT.
Cc: Allison Henderson <allison.henderson@oracle.com>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20250512092736.229935-16-bigeasy@linutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to '')
| -rw-r--r-- | net/rds/page.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/net/rds/page.c b/net/rds/page.c index 58a8548a915a..afb151eac271 100644 --- a/net/rds/page.c +++ b/net/rds/page.c @@ -40,10 +40,12 @@ struct rds_page_remainder { struct page *r_page; unsigned long r_offset; + local_lock_t bh_lock; }; -static -DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders); +static DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders) = { + .bh_lock = INIT_LOCAL_LOCK(bh_lock), +}; /** * rds_page_remainder_alloc - build up regions of a message. @@ -87,6 +89,7 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, } local_bh_disable(); + local_lock_nested_bh(&rds_page_remainders.bh_lock); rem = this_cpu_ptr(&rds_page_remainders); while (1) { @@ -115,11 +118,13 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, } /* alloc if there is nothing for us to use */ + local_unlock_nested_bh(&rds_page_remainders.bh_lock); local_bh_enable(); page = alloc_page(gfp); local_bh_disable(); + local_lock_nested_bh(&rds_page_remainders.bh_lock); rem = this_cpu_ptr(&rds_page_remainders); if (!page) { @@ -138,6 +143,7 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, rem->r_offset = 0; } + local_unlock_nested_bh(&rds_page_remainders.bh_lock); local_bh_enable(); out: rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret, |