diff options
| author | Sebastian Sewior <bigeasy@linutronix.de> | 2025-01-23 17:20:45 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-02-08 10:02:10 +0100 |
| commit | 74078892c6117a50215a11334db2b0fcba67ee81 (patch) | |
| tree | 1956c1fa26bd4a018b9f6433c2e39d4cfef8bd4b /net | |
| parent | b3c0a89d6cf1693e895a33e323be06082eb861ad (diff) | |
| download | linux-74078892c6117a50215a11334db2b0fcba67ee81.tar.gz linux-74078892c6117a50215a11334db2b0fcba67ee81.tar.bz2 linux-74078892c6117a50215a11334db2b0fcba67ee81.zip | |
xfrm: Don't disable preemption while looking up cache state.
[ Upstream commit 6c9b7db96db62ee9ad8d359d90ff468d462518c4 ]
For the state cache lookup xfrm_input_state_lookup() first disables
preemption, to remain on the CPU and then retrieves a per-CPU pointer.
Within the preempt-disable section it also acquires
netns_xfrm::xfrm_state_lock, a spinlock_t. This lock must not be
acquired with explicit disabled preemption (such as by get_cpu())
because this lock becomes a sleeping lock on PREEMPT_RT.
To remain on the same CPU is just an optimisation for the CPU local
lookup. The actual modification of the per-CPU variable happens with
netns_xfrm::xfrm_state_lock acquired.
Remove get_cpu() and use the state_cache_input on the current CPU.
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Closes: https://lore.kernel.org/all/CAADnVQKkCLaj=roayH=Mjiiqz_svdf1tsC3OE4EC0E=mAD+L1A@mail.gmail.com/
Fixes: 81a331a0e72dd ("xfrm: Add an inbound percpu state cache.")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/xfrm/xfrm_state.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 1781728ca428..711e816fc404 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -1150,9 +1150,8 @@ struct xfrm_state *xfrm_input_state_lookup(struct net *net, u32 mark, struct xfrm_hash_state_ptrs state_ptrs; struct hlist_head *state_cache_input; struct xfrm_state *x = NULL; - int cpu = get_cpu(); - state_cache_input = per_cpu_ptr(net->xfrm.state_cache_input, cpu); + state_cache_input = raw_cpu_ptr(net->xfrm.state_cache_input); rcu_read_lock(); hlist_for_each_entry_rcu(x, state_cache_input, state_cache_input) { @@ -1186,7 +1185,6 @@ struct xfrm_state *xfrm_input_state_lookup(struct net *net, u32 mark, out: rcu_read_unlock(); - put_cpu(); return x; } EXPORT_SYMBOL(xfrm_input_state_lookup); |