diff options
| author | KP Singh <kpsingh@kernel.org> | 2022-04-18 15:51:58 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-06 08:47:56 +0200 |
| commit | cf4b46ea392d75cc06800be7397d58d54453c6f3 (patch) | |
| tree | ca53347419adbe6a4b08b0c9217a34b523651afb /kernel/bpf/bpf_local_storage.c | |
| parent | 460318277b7ad2486ec3029ec0bf46edf99a1e3c (diff) | |
bpf: Fix usage of trace RCU in local storage.
commit dcf456c9a095a6e71f53d6f6f004133ee851ee70 upstream.
bpf_{sk,task,inode}_storage_free() do not need to use
call_rcu_tasks_trace as no BPF program should be accessing the owner
as it's being destroyed. The only other reader at this point is
bpf_local_storage_map_free() which uses normal RCU.
The only path that needs trace RCU are:
* bpf_local_storage_{delete,update} helpers
* map_{delete,update}_elem() syscalls
Fixes: 0fe4b381a59e ("bpf: Allow bpf_local_storage to be used by sleepable programs")
Signed-off-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220418155158.2865678-1-kpsingh@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/bpf/bpf_local_storage.c')
| -rw-r--r-- | kernel/bpf/bpf_local_storage.c | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index 71de2a89869c..79a8edfa7a2f 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -106,7 +106,7 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu) */ bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, struct bpf_local_storage_elem *selem, - bool uncharge_mem) + bool uncharge_mem, bool use_trace_rcu) { struct bpf_local_storage_map *smap; bool free_local_storage; @@ -150,11 +150,16 @@ bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, SDATA(selem)) RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL); - call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_rcu); + if (use_trace_rcu) + call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_rcu); + else + kfree_rcu(selem, rcu); + return free_local_storage; } -static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem) +static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem, + bool use_trace_rcu) { struct bpf_local_storage *local_storage; bool free_local_storage = false; @@ -169,12 +174,16 @@ static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem) raw_spin_lock_irqsave(&local_storage->lock, flags); if (likely(selem_linked_to_storage(selem))) free_local_storage = bpf_selem_unlink_storage_nolock( - local_storage, selem, true); + local_storage, selem, true, use_trace_rcu); raw_spin_unlock_irqrestore(&local_storage->lock, flags); - if (free_local_storage) - call_rcu_tasks_trace(&local_storage->rcu, + if (free_local_storage) { + if (use_trace_rcu) + call_rcu_tasks_trace(&local_storage->rcu, bpf_local_storage_free_rcu); + else + kfree_rcu(local_storage, rcu); + } } void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, @@ -214,14 +223,14 @@ void bpf_selem_link_map(struct bpf_local_storage_map *smap, raw_spin_unlock_irqrestore(&b->lock, flags); } -void bpf_selem_unlink(struct bpf_local_storage_elem *selem) +void bpf_selem_unlink(struct bpf_local_storage_elem *selem, bool use_trace_rcu) { /* Always unlink from map before unlinking from local_storage * because selem will be freed after successfully unlinked from * the local_storage. */ bpf_selem_unlink_map(selem); - __bpf_selem_unlink_storage(selem); + __bpf_selem_unlink_storage(selem, use_trace_rcu); } struct bpf_local_storage_data * @@ -454,7 +463,7 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap, if (old_sdata) { bpf_selem_unlink_map(SELEM(old_sdata)); bpf_selem_unlink_storage_nolock(local_storage, SELEM(old_sdata), - false); + false, true); } unlock: @@ -532,7 +541,7 @@ void bpf_local_storage_map_free(struct bpf_local_storage_map *smap, migrate_disable(); __this_cpu_inc(*busy_counter); } - bpf_selem_unlink(selem); + bpf_selem_unlink(selem, false); if (busy_counter) { __this_cpu_dec(*busy_counter); migrate_enable(); |