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authorJens Axboe <axboe@kernel.dk>2023-10-21 12:30:29 -0600
committerJens Axboe <axboe@kernel.dk>2023-10-25 07:44:14 -0600
commit7644b1a1c9a7ae8ab99175989bfc8676055edb46 (patch)
treedfa13e49521a00400a40c955f9f927a2e41c9af4 /io_uring
parent8b51a3956d44ea6ade962874ade14de9a7d16556 (diff)
io_uring/fdinfo: lock SQ thread while retrieving thread cpu/pid
We could race with SQ thread exit, and if we do, we'll hit a NULL pointer dereference when the thread is cleared. Grab the SQPOLL data lock before attempting to get the task cpu and pid for fdinfo, this ensures we have a stable view of it. Cc: stable@vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=218032 Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring')
-rw-r--r--io_uring/fdinfo.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/io_uring/fdinfo.c b/io_uring/fdinfo.c
index c53678875416..f04a43044d91 100644
--- a/io_uring/fdinfo.c
+++ b/io_uring/fdinfo.c
@@ -53,7 +53,6 @@ static __cold int io_uring_show_cred(struct seq_file *m, unsigned int id,
__cold void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
{
struct io_ring_ctx *ctx = f->private_data;
- struct io_sq_data *sq = NULL;
struct io_overflow_cqe *ocqe;
struct io_rings *r = ctx->rings;
unsigned int sq_mask = ctx->sq_entries - 1, cq_mask = ctx->cq_entries - 1;
@@ -64,6 +63,7 @@ __cold void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
unsigned int cq_shift = 0;
unsigned int sq_shift = 0;
unsigned int sq_entries, cq_entries;
+ int sq_pid = -1, sq_cpu = -1;
bool has_lock;
unsigned int i;
@@ -143,13 +143,19 @@ __cold void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
has_lock = mutex_trylock(&ctx->uring_lock);
if (has_lock && (ctx->flags & IORING_SETUP_SQPOLL)) {
- sq = ctx->sq_data;
- if (!sq->thread)
- sq = NULL;
+ struct io_sq_data *sq = ctx->sq_data;
+
+ if (mutex_trylock(&sq->lock)) {
+ if (sq->thread) {
+ sq_pid = task_pid_nr(sq->thread);
+ sq_cpu = task_cpu(sq->thread);
+ }
+ mutex_unlock(&sq->lock);
+ }
}
- seq_printf(m, "SqThread:\t%d\n", sq ? task_pid_nr(sq->thread) : -1);
- seq_printf(m, "SqThreadCpu:\t%d\n", sq ? task_cpu(sq->thread) : -1);
+ seq_printf(m, "SqThread:\t%d\n", sq_pid);
+ seq_printf(m, "SqThreadCpu:\t%d\n", sq_cpu);
seq_printf(m, "UserFiles:\t%u\n", ctx->nr_user_files);
for (i = 0; has_lock && i < ctx->nr_user_files; i++) {
struct file *f = io_file_from_index(&ctx->file_table, i);