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Date: Fri, 3 May 2013 14:04:09 -0700
From: Colin Cross <ccross@...roid.com>
To: linux-kernel@...r.kernel.org
Cc: Trond Myklebust <Trond.Myklebust@...app.com>,
Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
"J. Bruce Fields" <bfields@...ldses.org>,
"David S. Miller" <davem@...emloft.net>,
Andrew Morton <akpm@...ux-foundation.org>,
Mandeep Singh Baines <msb@...omium.org>,
Paul Walmsley <paul@...an.com>,
Colin Cross <ccross@...roid.com>,
Al Viro <viro@...iv.linux.org.uk>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Oleg Nesterov <oleg@...hat.com>, linux-nfs@...r.kernel.org,
linux-pm@...r.kernel.org, netdev@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Tejun Heo <tj@...nel.org>, Ben Chan <benchan@...omium.org>
Subject: [PATCH 1/2] freezer: add unsafe versions of freezable helpers
NFS calls the freezable helpers with locks held, which is unsafe
and caused lockdep warnings when 6aa9707 "lockdep: check that no
locks held at freeze time" was applied (reverted in dbf520a).
Add new *_unsafe versions of the helpers that will not run the
lockdep test when 6aa9707 is reapplied, and call them from NFS.
Signed-off-by: Colin Cross <ccross@...roid.com>
---
fs/nfs/inode.c | 2 +-
fs/nfs/nfs3proc.c | 2 +-
fs/nfs/nfs4proc.c | 4 ++--
include/linux/freezer.h | 42 +++++++++++++++++++++++++++++++++++++++++-
net/sunrpc/sched.c | 2 +-
5 files changed, 46 insertions(+), 6 deletions(-)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 1f94167..53cbee5 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -79,7 +79,7 @@ int nfs_wait_bit_killable(void *word)
{
if (fatal_signal_pending(current))
return -ERESTARTSYS;
- freezable_schedule();
+ freezable_schedule_unsafe();
return 0;
}
EXPORT_SYMBOL_GPL(nfs_wait_bit_killable);
diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 43ea96c..ce90eb4 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -33,7 +33,7 @@ nfs3_rpc_wrapper(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
res = rpc_call_sync(clnt, msg, flags);
if (res != -EJUKEBOX)
break;
- freezable_schedule_timeout_killable(NFS_JUKEBOX_RETRY_TIME);
+ freezable_schedule_timeout_killable_unsafe(NFS_JUKEBOX_RETRY_TIME);
res = -ERESTARTSYS;
} while (!fatal_signal_pending(current));
return res;
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 0ad025e..a236077 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -266,7 +266,7 @@ static int nfs4_delay(struct rpc_clnt *clnt, long *timeout)
*timeout = NFS4_POLL_RETRY_MIN;
if (*timeout > NFS4_POLL_RETRY_MAX)
*timeout = NFS4_POLL_RETRY_MAX;
- freezable_schedule_timeout_killable(*timeout);
+ freezable_schedule_timeout_killable_unsafe(*timeout);
if (fatal_signal_pending(current))
res = -ERESTARTSYS;
*timeout <<= 1;
@@ -4309,7 +4309,7 @@ int nfs4_proc_delegreturn(struct inode *inode, struct rpc_cred *cred, const nfs4
static unsigned long
nfs4_set_lock_task_retry(unsigned long timeout)
{
- freezable_schedule_timeout_killable(timeout);
+ freezable_schedule_timeout_killable_unsafe(timeout);
timeout <<= 1;
if (timeout > NFS4_LOCK_MAXTIMEOUT)
return NFS4_LOCK_MAXTIMEOUT;
diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index e70df40..5b31e21c 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -46,7 +46,11 @@ extern int freeze_kernel_threads(void);
extern void thaw_processes(void);
extern void thaw_kernel_threads(void);
-static inline bool try_to_freeze(void)
+/*
+ * DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION
+ * If try_to_freeze causes a lockdep warning it means the caller may deadlock
+ */
+static inline bool try_to_freeze_unsafe(void)
{
might_sleep();
if (likely(!freezing(current)))
@@ -54,6 +58,11 @@ static inline bool try_to_freeze(void)
return __refrigerator(false);
}
+static inline bool try_to_freeze(void)
+{
+ return try_to_freeze_unsafe();
+}
+
extern bool freeze_task(struct task_struct *p);
extern bool set_freezable(void);
@@ -115,6 +124,14 @@ static inline void freezer_count(void)
try_to_freeze();
}
+/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
+static inline void freezer_count_unsafe(void)
+{
+ current->flags &= ~PF_FREEZER_SKIP;
+ smp_mb();
+ try_to_freeze_unsafe();
+}
+
/**
* freezer_should_skip - whether to skip a task when determining frozen
* state is reached
@@ -152,6 +169,14 @@ static inline bool freezer_should_skip(struct task_struct *p)
freezer_count(); \
})
+/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
+#define freezable_schedule_unsafe() \
+({ \
+ freezer_do_not_count(); \
+ schedule(); \
+ freezer_count_unsafe(); \
+})
+
/* Like schedule_timeout_killable(), but should not block the freezer. */
#define freezable_schedule_timeout_killable(timeout) \
({ \
@@ -162,6 +187,16 @@ static inline bool freezer_should_skip(struct task_struct *p)
__retval; \
})
+/* DO NOT ADD ANY NEW CALLERS OF THIS FUNCTION */
+#define freezable_schedule_timeout_killable_unsafe(timeout) \
+({ \
+ long __retval; \
+ freezer_do_not_count(); \
+ __retval = schedule_timeout_killable(timeout); \
+ freezer_count_unsafe(); \
+ __retval; \
+})
+
/*
* Freezer-friendly wrappers around wait_event_interruptible(),
* wait_event_killable() and wait_event_interruptible_timeout(), originally
@@ -225,9 +260,14 @@ static inline void set_freezable(void) {}
#define freezable_schedule() schedule()
+#define freezable_schedule_unsafe() schedule()
+
#define freezable_schedule_timeout_killable(timeout) \
schedule_timeout_killable(timeout)
+#define freezable_schedule_timeout_killable_unsafe(timeout) \
+ schedule_timeout_killable(timeout)
+
#define wait_event_freezable(wq, condition) \
wait_event_interruptible(wq, condition)
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index f8529fc..8dcfadc 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -254,7 +254,7 @@ static int rpc_wait_bit_killable(void *word)
{
if (fatal_signal_pending(current))
return -ERESTARTSYS;
- freezable_schedule();
+ freezable_schedule_unsafe();
return 0;
}
--
1.8.2.1
--
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