On Wed, 2016-02-03 at 10:45 +0000, Ian Campbell wrote:
> On Tue, 2016-02-02 at 20:23 -0800, scan-ad...@coverity.com wrote:
> > * CID 1351223: Concurrent data access violations (MISSING_LOCK)
> > /xen/include/xen/spinlock.h: 362 in _percpu_write_unlock()
>
> Coverity seems to think this is new in 41b0aa569adb..9937763265d,
> presumably due to
>
> commit f9dd43dddc0a31a4343a58072935c1b5c0cbbee
> Author: Malcolm Crossley <malcolm.cross...@citrix.com>
> Date: Fri Jan 22 16:04:41 2016 +0100
>
> rwlock: add per-cpu reader-writer lock infrastructure
It also reports this one, but I suppose this is a false +ve given the name
of the function.
(Also note "simulatenously" should be "simultaneously")
** CID 1351220: Program hangs (LOCK)
/xen/include/xen/spinlock.h: 310 in _percpu_read_lock()
________________________________________________________________________________________________________
*** CID 1351220: Program hangs (LOCK)
/xen/include/xen/spinlock.h: 310 in _percpu_read_lock()
304 * Detect using a second percpu_rwlock_t simulatenously and
fallback
305 * to standard read_lock.
306 */
307 if ( unlikely(this_cpu_ptr(per_cpudata) != NULL ) )
308 {
309 read_lock(&percpu_rwlock->rwlock);
>>> CID 1351220: Program hangs (LOCK)
>>> Returning without unlocking "percpu_rwlock->rwlock".
310 return;
311 }
312
313 /* Indicate this cpu is reading. */
314 this_cpu_ptr(per_cpudata) = percpu_rwlock;
315 smp_mb();
>
> > _______________________________________________________________________
> > __
> > _______________________________
> > *** CID 1351223: Concurrent data access violations (MISSING_LOCK)
> > /xen/include/xen/spinlock.h: 362 in _percpu_write_unlock()
> > 356 percpu_rwlock_t *percpu_rwlock)
> > 357 {
> > 358 /* Validate the correct per_cpudata variable has been
> > provided. */
> > 359 _percpu_rwlock_owner_check(per_cpudata, percpu_rwlock);
> > 360
> > 361 ASSERT(percpu_rwlock->writer_activating);
> > > > > CID 1351223: Concurrent data access violations
> > > > > (MISSING_LOCK)
> > > > > Accessing "percpu_rwlock->writer_activating" without holding
> > > > > lock
> > "percpu_rwlock.rwlock". Elsewhere, "percpu_rwlock.writer_activating" is
> > accessed with "percpu_rwlock.rwlock" held 1 out of 2 times (1 of these
> > accesses strongly imply that it is necessary).
> > 362 percpu_rwlock->writer_activating = 0;
> > 363 write_unlock(&percpu_rwlock->rwlock);
> > 364 }
> > 365
> > 366 #define percpu_rw_is_write_locked(l)
> > _rw_is_write_locked(&((l)->rwlock))
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