This issue is found by running liburing/test/io_uring_setup test.
When test run, the testcase "attempt to bind to invalid cpu" would not
pass with messages like:
io_uring_setup(1, 0xbfc2f7c8), \
flags: IORING_SETUP_SQPOLL|IORING_SETUP_SQ_AFF, \
resv: 0x00000000 0x00000000 0x00000000 0x00000000 0x00000000, \
sq_thread_cpu: 2
expected -1, got 3
FAIL
On my system, there is:
CPU(s) possible : 0-3
CPU(s) online : 0-1
CPU(s) offline : 2-3
CPU(s) present : 0-1
The sq_thread_cpu 2 is offline on my system, so the bind should fail.
But cpu_possible() will pass the check. We shouldn't be able to bind
to an offline cpu. Use cpu_online() to do the check.
After the change, the testcase run as expected: EINVAL will be returned
for cpu offlined.
Signed-off-by: Shenghui Wang <shhuiw@xxxxxxxxxxx>
---
fs/io_uring.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 0e9fb2cb1984..aa3d39860a1c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2241,7 +2241,7 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
ctx->sqo_mm = current->mm;
ret = -EINVAL;
- if (!cpu_possible(p->sq_thread_cpu))
+ if (!cpu_online(p->sq_thread_cpu))
goto err;
if (ctx->flags & IORING_SETUP_SQPOLL) {
@@ -2258,7 +2258,7 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
cpu = array_index_nospec(p->sq_thread_cpu, NR_CPUS);
ret = -EINVAL;
- if (!cpu_possible(p->sq_thread_cpu))
+ if (!cpu_online(p->sq_thread_cpu))
goto err;
ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread,
--
2.20.1
