This is a note to let you know that I've just added the patch titled
cachefiles: make on-demand read killable
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cachefiles-make-on-demand-read-killable.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 40c6f12bec7fe2fb2622b780635c2b66f91f5bda
Author: Baokun Li <libaokun1@xxxxxxxxxx>
Date: Wed May 22 19:43:08 2024 +0800
cachefiles: make on-demand read killable
[ Upstream commit bc9dde6155464e906e630a0a5c17a4cab241ffbb ]
Replacing wait_for_completion() with wait_for_completion_killable() in
cachefiles_ondemand_send_req() allows us to kill processes that might
trigger a hunk_task if the daemon is abnormal.
But now only CACHEFILES_OP_READ is killable, because OP_CLOSE and OP_OPEN
is initiated from kworker context and the signal is prohibited in these
kworker.
Note that when the req in xas changes, i.e. xas_load(&xas) != req, it
means that a process will complete the current request soon, so wait
again for the request to be completed.
In addition, add the cachefiles_ondemand_finish_req() helper function to
simplify the code.
Suggested-by: Hou Tao <houtao1@xxxxxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240522114308.2402121-13-libaokun@xxxxxxxxxxxxxxx
Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
Reviewed-by: Jia Zhu <zhujia.zj@xxxxxxxxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c
index a0e34581a1cd6..d0059d36cbd51 100644
--- a/fs/cachefiles/ondemand.c
+++ b/fs/cachefiles/ondemand.c
@@ -380,6 +380,20 @@ static struct cachefiles_req *cachefiles_ondemand_select_req(struct xa_state *xa
return NULL;
}
+static inline bool cachefiles_ondemand_finish_req(struct cachefiles_req *req,
+ struct xa_state *xas, int err)
+{
+ if (unlikely(!xas || !req))
+ return false;
+
+ if (xa_cmpxchg(xas->xa, xas->xa_index, req, NULL, 0) != req)
+ return false;
+
+ req->error = err;
+ complete(&req->done);
+ return true;
+}
+
ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
char __user *_buffer, size_t buflen)
{
@@ -443,16 +457,8 @@ ssize_t cachefiles_ondemand_daemon_read(struct cachefiles_cache *cache,
out:
cachefiles_put_object(req->object, cachefiles_obj_put_read_req);
/* Remove error request and CLOSE request has no reply */
- if (ret || msg->opcode == CACHEFILES_OP_CLOSE) {
- xas_reset(&xas);
- xas_lock(&xas);
- if (xas_load(&xas) == req) {
- req->error = ret;
- complete(&req->done);
- xas_store(&xas, NULL);
- }
- xas_unlock(&xas);
- }
+ if (ret || msg->opcode == CACHEFILES_OP_CLOSE)
+ cachefiles_ondemand_finish_req(req, &xas, ret);
cachefiles_req_put(req);
return ret ? ret : n;
}
@@ -557,8 +563,18 @@ static int cachefiles_ondemand_send_req(struct cachefiles_object *object,
goto out;
wake_up_all(&cache->daemon_pollwq);
- wait_for_completion(&req->done);
- ret = req->error;
+wait:
+ ret = wait_for_completion_killable(&req->done);
+ if (!ret) {
+ ret = req->error;
+ } else {
+ ret = -EINTR;
+ if (!cachefiles_ondemand_finish_req(req, &xas, ret)) {
+ /* Someone will complete it soon. */
+ cpu_relax();
+ goto wait;
+ }
+ }
cachefiles_req_put(req);
return ret;
out:
