linux-kernel - [PATCH] freezer: Add unsafe versions of freezable_schedule_timeout

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Message-ID: <20200706095224.2285480-1-zhe.he@windriver.com>
Date:   Mon, 6 Jul 2020 17:52:24 +0800
From:   <zhe.he@...driver.com>
To:     <trond.myklebust@...merspace.com>, <anna.schumaker@...app.com>,
        <rjw@...ysocki.net>, <len.brown@...el.com>, <pavel@....cz>,
        <linux-nfs@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <zhe.he@...driver.com>
Subject: [PATCH] freezer: Add unsafe versions of freezable_schedule_timeout_interruptible for NFS

From: He Zhe <zhe.he@...driver.com>

commit 0688e64bc600 ("NFS: Allow signal interruption of NFS4ERR_DELAYed operations")
introduces nfs4_delay_interruptible which also needs an _unsafe version to
avoid the following call trace for the same reason explained in
commit 416ad3c9c006 ("freezer: add unsafe versions of freezable helpers for NFS")

CPU: 4 PID: 3968 Comm: rm Tainted: G W 5.8.0-rc4 #1
Hardware name: Marvell OcteonTX CN96XX board (DT)
Call trace:
dump_backtrace+0x0/0x1dc
show_stack+0x20/0x30
dump_stack+0xdc/0x150
debug_check_no_locks_held+0x98/0xa0
nfs4_delay_interruptible+0xd8/0x120
nfs4_handle_exception+0x130/0x170
nfs4_proc_rmdir+0x8c/0x220
nfs_rmdir+0xa4/0x360
vfs_rmdir.part.0+0x6c/0x1b0
do_rmdir+0x18c/0x210
__arm64_sys_unlinkat+0x64/0x7c
el0_svc_common.constprop.0+0x7c/0x110
do_el0_svc+0x24/0xa0
el0_sync_handler+0x13c/0x1b8
el0_sync+0x158/0x180

Signed-off-by: He Zhe <zhe.he@...driver.com>
---
 fs/nfs/nfs4proc.c       |  2 +-
 include/linux/freezer.h | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e32717fd1169..15ecfa474e37 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -414,7 +414,7 @@ static int nfs4_delay_interruptible(long *timeout)
 {
 	might_sleep();
 
-	freezable_schedule_timeout_interruptible(nfs4_update_delay(timeout));
+	freezable_schedule_timeout_interruptible_unsafe(nfs4_update_delay(timeout));
 	if (!signal_pending(current))
 		return 0;
 	return __fatal_signal_pending(current) ? -EINTR :-ERESTARTSYS;
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 21f5aa0b217f..27828145ca09 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -207,6 +207,17 @@ static inline long freezable_schedule_timeout_interruptible(long timeout)
 	return __retval;
 }
 
+/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
+static inline long freezable_schedule_timeout_interruptible_unsafe(long timeout)
+{
+	long __retval;
+
+	freezer_do_not_count();
+	__retval = schedule_timeout_interruptible(timeout);
+	freezer_count_unsafe();
+	return __retval;
+}
+
 /* Like schedule_timeout_killable(), but should not block the freezer. */
 static inline long freezable_schedule_timeout_killable(long timeout)
 {
@@ -285,6 +296,9 @@ static inline void set_freezable(void) {}
 #define freezable_schedule_timeout_interruptible(timeout)		\
 	schedule_timeout_interruptible(timeout)
 
+#define freezable_schedule_timeout_interruptible_unsafe(timeout)	\
+	schedule_timeout_interruptible(timeout)
+
 #define freezable_schedule_timeout_killable(timeout)			\
 	schedule_timeout_killable(timeout)
 
-- 
2.17.1