From 2529b3a80e1bf1713c0ecbedb246654a0968b4d2 Mon Sep 17 00:00:00 2001
From: tuxoko <tuxoko@gmail.com>
Date: Fri, 7 Oct 2016 20:53:58 -0700
Subject: [PATCH] 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 <behlendorf1@llnl.gov>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes zfsonlinux/zfs#5233
Closes #577
---
include/sys/rwlock.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/sys/rwlock.h b/include/sys/rwlock.h
index facebe3ba7..4197785db1 100644
--- a/include/sys/rwlock.h
+++ b/include/sys/rwlock.h
@@ -114,7 +114,12 @@ spl_rw_lockdep_on_maybe(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