Hello,
My static analysis tool reports several possible ABBA deadlock in the
rdmavt driver in Linux 5.18:
rvt_ruc_loopback()
spin_lock_irqsave(&sqp->s_lock, flags); --> Line 3190 (Lock A)
spin_lock(&sqp->r_lock); --> Line 3195 (Lock B)
rvt_qp_mr_clean()
spin_lock_irq(&qp->r_lock); --> Line 698 (Lock B)
spin_lock(&qp->s_lock); --> Line 700 (Lock A)
rvt_rc_timeout()
spin_lock_irqsave(&qp->r_lock, flags); --> Line 2595 (Lock B)
spin_lock(&qp->s_lock); --> Line 2596 (Lock A)
rvt_modify_qp()
spin_lock_irq(&qp->r_lock); --> Line 1419 (Lock B)
spin_lock(&qp->s_lock); --> Line 1421(Lock A)
_rvt_reset_qp()
spin_lock_irq(&qp->r_lock); --> Line 907 (Lock B)
spin_lock(&qp->s_lock); --> Line 909 (Lock A)
rvt_reset_qp()
spin_lock_irq(&qp->r_lock); --> Line 936 (Lock B)
spin_lock(&qp->s_lock); --> Line 938 (Lock A)
When rvt_ruc_loopback() is concurrently executed with rvt_qp_mr_clean(),
rvt_rc_timeout(), rvt_modify_qp(), _rvt_reset_qp() or rvt_reset_qp(),
the deadlocks can occur.
I am not quite sure whether these possible deadlocks are real and how to
fix them if real.
Any feedback would be appreciated, thanks :)
Reported-by: TOTE Robot <[email protected]>
Best wishes,
Jia-Ju Bai
On 10/20/22 9:37 AM, Jia-Ju Bai wrote:
> Hello,
>
> My static analysis tool reports several possible ABBA deadlock in the
> rdmavt driver in Linux 5.18:
>
> rvt_ruc_loopback()
> spin_lock_irqsave(&sqp->s_lock, flags); --> Line 3190 (Lock A)
> spin_lock(&sqp->r_lock); --> Line 3195 (Lock B)
>
> rvt_qp_mr_clean()
> spin_lock_irq(&qp->r_lock); --> Line 698 (Lock B)
> spin_lock(&qp->s_lock); --> Line 700 (Lock A)
>
> rvt_rc_timeout()
> spin_lock_irqsave(&qp->r_lock, flags); --> Line 2595 (Lock B)
> spin_lock(&qp->s_lock); --> Line 2596 (Lock A)
>
> rvt_modify_qp()
> spin_lock_irq(&qp->r_lock); --> Line 1419 (Lock B)
> spin_lock(&qp->s_lock); --> Line 1421(Lock A)
>
> _rvt_reset_qp()
> spin_lock_irq(&qp->r_lock); --> Line 907 (Lock B)
> spin_lock(&qp->s_lock); --> Line 909 (Lock A)
>
> rvt_reset_qp()
> spin_lock_irq(&qp->r_lock); --> Line 936 (Lock B)
> spin_lock(&qp->s_lock); --> Line 938 (Lock A)
>
> When rvt_ruc_loopback() is concurrently executed with rvt_qp_mr_clean(),
> rvt_rc_timeout(), rvt_modify_qp(), _rvt_reset_qp() or rvt_reset_qp(),
> the deadlocks can occur.
>
> I am not quite sure whether these possible deadlocks are real and how to
> fix them if real.
> Any feedback would be appreciated, thanks :)
>
> Reported-by: TOTE Robot <[email protected]>
Thanks, we'll look into them.
-Denny
On 20/10/2022 15:37, Jia-Ju Bai wrote:
> Hello,
>
> My static analysis tool reports several possible ABBA deadlock in the rdmavt driver in Linux 5.18:
>
> rvt_ruc_loopback()
> spin_lock_irqsave(&sqp->s_lock, flags); --> Line 3190 (Lock A)
> spin_lock(&sqp->r_lock); --> Line 3195 (Lock B)
>
> rvt_qp_mr_clean()
> spin_lock_irq(&qp->r_lock); --> Line 698 (Lock B)
> spin_lock(&qp->s_lock); --> Line 700 (Lock A)
>
> rvt_rc_timeout()
> spin_lock_irqsave(&qp->r_lock, flags); --> Line 2595 (Lock B)
> spin_lock(&qp->s_lock); --> Line 2596 (Lock A)
>
> rvt_modify_qp()
> spin_lock_irq(&qp->r_lock); --> Line 1419 (Lock B)
> spin_lock(&qp->s_lock); --> Line 1421(Lock A)
>
> _rvt_reset_qp()
> spin_lock_irq(&qp->r_lock); --> Line 907 (Lock B)
> spin_lock(&qp->s_lock); --> Line 909 (Lock A)
>
> rvt_reset_qp()
> spin_lock_irq(&qp->r_lock); --> Line 936 (Lock B)
> spin_lock(&qp->s_lock); --> Line 938 (Lock A)
>
> When rvt_ruc_loopback() is concurrently executed with rvt_qp_mr_clean(), rvt_rc_timeout(), rvt_modify_qp(), _rvt_reset_qp() or rvt_reset_qp(), the deadlocks can occur.
>
> I am not quite sure whether these possible deadlocks are real and how to fix them if real.
> Any feedback would be appreciated, thanks :)
>
> Reported-by: TOTE Robot <[email protected]>
>
>
> Best wishes,
> Jia-Ju Bai
Hi
I don't know whether this deadlock is real or not, but I wrote the offending code.
If it's a real bug, I'm sorry about that.
If that's the case the bug is also present in 2 other places of rvt_ruc_loopback() in v5.19+:
1)
spin_lock_irqsave(&sqp->s_lock, flags); --> Line 3133
spin_lock(&sqp->r_lock); --> Line 3137
2)
spin_lock_irqsave(&sqp->s_lock, flags); --> Line 3192
spin_lock(&sqp->r_lock); --> Line 3193
Kind regards
Niels