From: libaokun@huaweicloud.com
To: netfs@lists.linux.dev, dhowells@redhat.com, jlayton@kernel.org
Cc: libaokun@huaweicloud.com, yangerkun@huawei.com,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
hsiangkao@linux.alibaba.com, linux-erofs@lists.ozlabs.org,
yukuai3@huawei.com
Subject: [PATCH v2 5/5] cachefiles: add missing lock protection when polling
Date: Wed, 15 May 2024 20:51:36 +0800 [thread overview]
Message-ID: <20240515125136.3714580-6-libaokun@huaweicloud.com> (raw)
In-Reply-To: <20240515125136.3714580-1-libaokun@huaweicloud.com>
From: Jingbo Xu <jefflexu@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 <jefflexu@linux.alibaba.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.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))
--
2.39.2
prev parent reply other threads:[~2024-05-15 13:02 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-15 12:51 [PATCH v2 0/5] cachefiles: some bugfixes for clean object/send req/poll libaokun
2024-05-15 12:51 ` [PATCH v2 1/5] cachefiles: stop sending new request when dropping object libaokun
2024-05-15 12:51 ` [PATCH v2 2/5] cachefiles: flush all requests for the object that is being dropped libaokun
2024-05-15 12:51 ` [PATCH v2 3/5] cachefiles: flush ondemand_object_worker during clean object libaokun
2024-05-15 12:51 ` [PATCH v2 4/5] cachefiles: cyclic allocation of msg_id to avoid reuse libaokun
2024-05-19 11:11 ` Jeff Layton
2024-05-20 4:06 ` Baokun Li
2024-05-20 10:04 ` Jeff Layton
2024-05-20 12:42 ` Baokun Li
2024-05-20 12:54 ` Gao Xiang
2024-05-20 13:24 ` Baokun Li
2024-05-20 14:56 ` Gao Xiang
2024-05-21 2:36 ` Baokun Li
2024-05-21 2:53 ` Gao Xiang
2024-05-20 13:24 ` Jeff Layton
2024-05-15 12:51 ` libaokun [this message]
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