在 2024/4/24 11:34, libao...@huaweicloud.com 写道:
From: Jingbo Xu <jeffl...@linux.alibaba.com>
Add missing lock protection in poll routine when iterating xarray,
otherwise:
Even with RCU read lock held, only the slot of the radix tree is
ensured to be pinned there, while the data structure (e.g. struct
cachefiles_req) stored in the slot has no such guarantee. The poll
routine will iterate the radix tree and dereference cachefiles_req
accordingly. Thus RCU read lock is not adequate in this case and
spinlock is needed here.
Fixes: b817e22b2e91 ("cachefiles: narrow the scope of triggering EPOLLIN events in
ondemand mode")
Signed-off-by: Jingbo Xu <jeffl...@linux.alibaba.com>
Reviewed-by: Joseph Qi <joseph...@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiang...@linux.alibaba.com>
Signed-off-by: Baokun Li <libaok...@huawei.com>
Thanks for catching this.
Reviewed-by: Jia Zhu <zhujia...@bytedance.com>
---
fs/cachefiles/daemon.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
index 6465e2574230..73ed2323282a 100644
--- a/fs/cachefiles/daemon.c
+++ b/fs/cachefiles/daemon.c
@@ -365,14 +365,14 @@ static __poll_t cachefiles_daemon_poll(struct file *file,
if (cachefiles_in_ondemand_mode(cache)) {
if (!xa_empty(&cache->reqs)) {
- rcu_read_lock();
+ xas_lock(&xas);
xas_for_each_marked(&xas, req, ULONG_MAX,
CACHEFILES_REQ_NEW) {
if
(!cachefiles_ondemand_is_reopening_read(req)) {
mask |= EPOLLIN;
break;
}
}
- rcu_read_unlock();
+ xas_unlock(&xas);
}
} else {
if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
