linux-kernel - [PATCH 4.9 32/78] xfs: fix spurious spin_is_locked() assert failures on non-smp kernels

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Date:   Mon, 18 Sep 2017 11:11:41 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, kbuild test robot <fengguang.wu@...el.com>,
        Brian Foster <bfoster@...hat.com>,
        Christoph Hellwig <hch@....de>,
        "Darrick J. Wong" <darrick.wong@...cle.com>
Subject: [PATCH 4.9 32/78] xfs: fix spurious spin_is_locked() assert failures on non-smp kernels

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Brian Foster <bfoster@...hat.com>

commit 95989c46d2a156365867b1d795fdefce71bce378 upstream.

The 0-day kernel test robot reports assertion failures on
!CONFIG_SMP kernels due to failed spin_is_locked() checks. As it
turns out, spin_is_locked() is hardcoded to return zero on
!CONFIG_SMP kernels and so this function cannot be relied on to
verify spinlock state in this configuration.

To avoid this problem, replace the associated asserts with lockdep
variants that do the right thing regardless of kernel configuration.
Drop the one assert that checks for an unlocked lock as there is no
suitable lockdep variant for that case. This moves the spinlock
checks from XFS debug code to lockdep, but generally provides the
same level of protection.

Reported-by: kbuild test robot <fengguang.wu@...el.com>
Signed-off-by: Brian Foster <bfoster@...hat.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/xfs/xfs_buf.c    |    2 +-
 fs/xfs/xfs_icache.c |    5 ++---
 2 files changed, 3 insertions(+), 4 deletions(-)

--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -116,7 +116,7 @@ static inline void
 __xfs_buf_ioacct_dec(
 	struct xfs_buf	*bp)
 {
-	ASSERT(spin_is_locked(&bp->b_lock));
+	lockdep_assert_held(&bp->b_lock);

 	if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
 		bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -66,7 +66,6 @@ xfs_inode_alloc(

 	XFS_STATS_INC(mp, vn_active);
 	ASSERT(atomic_read(&ip->i_pincount) == 0);
-	ASSERT(!spin_is_locked(&ip->i_flags_lock));
 	ASSERT(!xfs_isiflocked(ip));
 	ASSERT(ip->i_ino == 0);

@@ -192,7 +191,7 @@ xfs_perag_set_reclaim_tag(
 {
 	struct xfs_mount	*mp = pag->pag_mount;

-	ASSERT(spin_is_locked(&pag->pag_ici_lock));
+	lockdep_assert_held(&pag->pag_ici_lock);
 	if (pag->pag_ici_reclaimable++)
 		return;

@@ -214,7 +213,7 @@ xfs_perag_clear_reclaim_tag(
 {
 	struct xfs_mount	*mp = pag->pag_mount;

-	ASSERT(spin_is_locked(&pag->pag_ici_lock));
+	lockdep_assert_held(&pag->pag_ici_lock);
 	if (--pag->pag_ici_reclaimable)
 		return;