Re: Detect double-release of spinlock

Andres Freund <andres@anarazel.de>

From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers@postgresql.org
Date: 2024-07-29T17:48:53Z
Lists: pgsql-hackers
Hi,

On 2024-07-29 13:25:22 -0400, Tom Lane wrote:
> Heikki Linnakangas <hlinnaka@iki.fi> writes:
> > Yeah I'm not worried about that at all. Also, the assert is made when 
> > you have already released the spinlock; you are already out of the 
> > critical section.
> 
> Not in the patch Andres posted.

Which seems fairly fundamental - once outside of the critical section, we
can't actually assert that the lock isn't acquired, somebody else *validly*
might have acquired it by then.

However, I still don't think it's a problem to assert that the lock is held in
in the unlock "routine". As mentioned before, the spinlock implementation
itself has never followed the "just straight line code" rule that users of
spinlocks are supposed to follow.

Greetings,

Andres Freund



Commits

  1. Fix double-release of spinlock

  2. Move cancel key generation to after forking the backend