Fix potential race condition in linux stat(2)

[trasz]

Summary

Fix potential race condition in linux stat(2).

[trasz]

(Tinderboxed.)

[kib]

sys/compat/linux/linux_util.c

206 ↗

(On Diff #74301)

Can we use vnode lock to guarantee liveness of the v_rdev read ? This is how it was intended.

[trasz]

sys/compat/linux/linux_util.c

206 ↗

(On Diff #74301)

Do we need to? I've looked at vn_isdisk(), and it doesn't seem to use the vnode lock.

[kib]

sys/compat/linux/linux_util.c

206 ↗

(On Diff #74301)

It uses dev_mtx, same as you did, which is global and already contended mutex.

Ok, it probably would be better to do the global sweep for vn_isdisk(), finishing mjg half-done change.