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Message-ID: <ojkrbtd2kpweo5xcfulfobdavj5ab3ysxxle4kr5oa455me77s@p2o4jdwsr3m2>
Date: Thu, 8 May 2025 12:47:18 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Mika Westerberg <westeri@...nel.org>
Cc: Andreas Noever <andreas.noever@...il.com>,
Michael Jamet <michael.jamet@...el.com>, Yehezkel Bernat <YehezkelShB@...il.com>,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org, stable@...r.kernel.org,
Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: Re: [PATCHv3] thunderbolt: do not double dequeue a request
On (25/03/28 00:03), Sergey Senozhatsky wrote:
> Some of our devices crash in tb_cfg_request_dequeue():
>
> general protection fault, probably for non-canonical address 0xdead000000000122
>
> CPU: 6 PID: 91007 Comm: kworker/6:2 Tainted: G U W 6.6.65
> RIP: 0010:tb_cfg_request_dequeue+0x2d/0xa0
> Call Trace:
> <TASK>
> ? tb_cfg_request_dequeue+0x2d/0xa0
> tb_cfg_request_work+0x33/0x80
> worker_thread+0x386/0x8f0
> kthread+0xed/0x110
> ret_from_fork+0x38/0x50
> ret_from_fork_asm+0x1b/0x30
>
> The circumstances are unclear, however, the theory is that
> tb_cfg_request_work() can be scheduled twice for a request:
> first time via frame.callback from ring_work() and second
> time from tb_cfg_request(). Both times kworkers will execute
> tb_cfg_request_dequeue(), which results in double list_del()
> from the ctl->request_queue (the list poison deference hints
> at it: 0xdead000000000122).
>
> Do not dequeue requests that don't have TB_CFG_REQUEST_ACTIVE
> bit set.
Mika, as was discussed in [1] thread we rolled out the fix to
our fleet and we don't see the crashes anymore. So it's tested
and verified.
[1] https://lore.kernel.org/linux-kernel/20250327145543.GC3152277@black.fi.intel.com
> ---
>
> v3: tweaked commit message
>
> drivers/thunderbolt/ctl.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/thunderbolt/ctl.c b/drivers/thunderbolt/ctl.c
> index cd15e84c47f4..1db2e951b53f 100644
> --- a/drivers/thunderbolt/ctl.c
> +++ b/drivers/thunderbolt/ctl.c
> @@ -151,6 +151,11 @@ static void tb_cfg_request_dequeue(struct tb_cfg_request *req)
> struct tb_ctl *ctl = req->ctl;
>
> mutex_lock(&ctl->request_queue_lock);
> + if (!test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags)) {
> + mutex_unlock(&ctl->request_queue_lock);
> + return;
> + }
> +
> list_del(&req->list);
> clear_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
> if (test_bit(TB_CFG_REQUEST_CANCELED, &req->flags))
> --
> 2.49.0.395.g12beb8f557-goog
>
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