Re: [Xen-devel] [PATCH v4 6/6] xen/rcu: add per-lock counter in debug builds

[Jürgen Groß <jgross@xxxxxxxx>]

On 11.03.20 13:14, Jan Beulich wrote:
> On 10.03.2020 08:28, Juergen Gross wrote:
> > Add a lock specific counter to rcu read locks in debug builds. This
> > allows to test for matching lock/unlock calls.
> Similar checking doesn't exist for e.g. spin locks iirc, and hence
> I think you want to spend the word on the "why" here.
With spinlock debugging turned on there is such a check in rel_lock():
The locking cpu has to match and on unlock the locking cpu is set to
SPINLOCK_NO_CPU.

I can add something like:

"This will help top avoid cases like the one fixed by commit
 98ed1f43cc2c89 where different rcu read locks were referenced in the
 lock and unlock calls."


Juergen

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