Re: [dm-devel] [PATCH] libmpathpersist: fix thread safety of default functions

[Martin Wilck <martin.wilck@suse.com>]

On Mon, 2021-01-25 at 23:31 -0600, Benjamin Marzinski wrote:
> commit a839e39e ("libmpathpersist: factor out initialization and
> teardown") made mpath_presistent_reserve_{in,out} use share variables
> for curmp and pathvec.  There are users of this library that call
> these
> functions in a multi-threaded process, and this change causes their
> application to crash. config and udev are also shared variables, but
> libmpathpersist doesn't write to the config in
> mpath_presistent_reserve_{in,out}, and looking into the libudev code,
> I
> don't see any place where libmpathpersist uses the udev object in a
> way
> that isn't thread-safe.
> 
> This patch makes mpath_presistent_reserve_{in,out} go back to using
> local variables for curmp and pathvec, so that multiple threads won't
> be operating on these variables at the same time.
> 
> Fixes: a839e39e ("libmpathpersist: factor out initialization and
> teardown")
> Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>

It turns out our CI has caught an actual bug for the first time :-)

https://github.com/openSUSE/multipath-tools/runs/1768201417?check_suite_focus=true#step:8:719

No need to resubmit, I'll just quickly amend this.

Regards
Martin


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