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rds: introduce acquire/release ordering in acquire/release_in_xmit()

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acquire/release_in_xmit() work as bit lock in rds_send_xmit(), so they
are expected to ensure acquire/release memory ordering semantics.
However, test_and_set_bit/clear_bit() don't imply such semantics, on
top of this, following smp_mb__after_atomic() does not guarantee release
ordering (memory barrier actually should be placed before clear_bit()).

Instead, we use clear_bit_unlock/test_and_set_bit_lock() here.

Fixes: 0f4b1c7e89 ("rds: fix rds_send_xmit() serialization")
Fixes: 1f9ecd7eac ("RDS: Pass rds_conn_path to rds_send_xmit()")
Signed-off-by: Yewon Choi <woni9911@gmail.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Link: https://lore.kernel.org/r/ZfQUxnNTO9AJmzwc@libra05
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Yewon Choi 2024-03-15 18:28:38 +09:00 committed by Paolo Abeni
parent 9966e329d6
commit 1422f28826
1 changed files with 2 additions and 3 deletions
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5
net/rds/send.c
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@ -103,13 +103,12 @@ EXPORT_SYMBOL_GPL(rds_send_path_reset);
static int acquire_in_xmit(struct rds_conn_path *cp)
{
return test_and_set_bit(RDS_IN_XMIT, &cp->cp_flags) == 0;
return test_and_set_bit_lock(RDS_IN_XMIT, &cp->cp_flags) == 0;
}
static void release_in_xmit(struct rds_conn_path *cp)
{
clear_bit(RDS_IN_XMIT, &cp->cp_flags);
smp_mb__after_atomic();
clear_bit_unlock(RDS_IN_XMIT, &cp->cp_flags);
/*
* We don't use wait_on_bit()/wake_up_bit() because our waking is in a
* hot path and finding waiters is very rare. We don't want to walk