Linux 4.8 compat: Fix RW_READ_HELD

Linux 4.8, starting from torvalds/linux@19c5d690e, will set owner to 1 when read held instead of leave it NULL. So we change the condition to `rw_owner(rwp) <= 1` in RW_READ_HELD. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Chunwei Chen <[email protected]> Closes openzfs/zfs#5233 Closes openzfs#577
behlendorf · Feb 1, 2017 · 1e94383 · 1e94383
1 parent f28d157
commit 1e94383
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/include/sys/rwlock.h b/include/sys/rwlock.h
@@ -83,7 +83,12 @@ rw_owner(krwlock_t *rwp)
 static inline int
 RW_READ_HELD(krwlock_t *rwp)
 {
-	return (spl_rwsem_is_locked(SEM(rwp)) && rw_owner(rwp) == NULL);
+	/*
+	 * Linux 4.8 will set owner to 1 when read held instead of leave it
+	 * NULL. So we check whether owner <= 1.
+	 */
+	return (spl_rwsem_is_locked(SEM(rwp)) &&
+	    (unsigned long)rw_owner(rwp) <= 1);
 }
 
 static inline int