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sched/wait: Fix the signal handling fix
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Jan Stancek reported that I wrecked things for him by fixing things for
Vladimir :/

His report was due to an UNINTERRUPTIBLE wait getting -EINTR, which
should not be possible, however my previous patch made this possible by
unconditionally checking signal_pending().

We cannot use current->state as was done previously, because the
instruction after the store to that variable it can be changed.  We must
instead pass the initial state along and use that.

Fixes: 6898563 ("sched/wait: Fix signal handling in bit wait helpers")
Reported-by: Jan Stancek <jstancek@redhat.com>
Reported-by: Chris Mason <clm@fb.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: Chris Mason <clm@fb.com>
Reviewed-by: Paul Turner <pjt@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: tglx@linutronix.de
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: hpa@zytor.com
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Peter Zijlstra authored and Linus Torvalds committed Dec 13, 2015
1 parent fc89182 commit dfd01f0
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Showing 8 changed files with 28 additions and 28 deletions.
6 changes: 3 additions & 3 deletions fs/cifs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1831,11 +1831,11 @@ cifs_invalidate_mapping(struct inode *inode)
* @word: long word containing the bit lock
*/
static int
cifs_wait_bit_killable(struct wait_bit_key *key)
cifs_wait_bit_killable(struct wait_bit_key *key, int mode)
{
if (fatal_signal_pending(current))
return -ERESTARTSYS;
freezable_schedule_unsafe();
if (signal_pending_state(mode, current))
return -ERESTARTSYS;
return 0;
}

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6 changes: 3 additions & 3 deletions fs/nfs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -75,11 +75,11 @@ nfs_fattr_to_ino_t(struct nfs_fattr *fattr)
* nfs_wait_bit_killable - helper for functions that are sleeping on bit locks
* @word: long word containing the bit lock
*/
int nfs_wait_bit_killable(struct wait_bit_key *key)
int nfs_wait_bit_killable(struct wait_bit_key *key, int mode)
{
if (fatal_signal_pending(current))
return -ERESTARTSYS;
freezable_schedule_unsafe();
if (signal_pending_state(mode, current))
return -ERESTARTSYS;
return 0;
}
EXPORT_SYMBOL_GPL(nfs_wait_bit_killable);
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2 changes: 1 addition & 1 deletion fs/nfs/internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -379,7 +379,7 @@ extern int nfs_drop_inode(struct inode *);
extern void nfs_clear_inode(struct inode *);
extern void nfs_evict_inode(struct inode *);
void nfs_zap_acl_cache(struct inode *inode);
extern int nfs_wait_bit_killable(struct wait_bit_key *key);
extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);

/* super.c */
extern const struct super_operations nfs_sops;
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2 changes: 1 addition & 1 deletion fs/nfs/pagelist.c
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Original file line number Diff line number Diff line change
Expand Up @@ -129,7 +129,7 @@ __nfs_iocounter_wait(struct nfs_io_counter *c)
set_bit(NFS_IO_INPROGRESS, &c->flags);
if (atomic_read(&c->io_count) == 0)
break;
ret = nfs_wait_bit_killable(&q.key);
ret = nfs_wait_bit_killable(&q.key, TASK_KILLABLE);
} while (atomic_read(&c->io_count) != 0 && !ret);
finish_wait(wq, &q.wait);
return ret;
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4 changes: 2 additions & 2 deletions fs/nfs/pnfs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1466,11 +1466,11 @@ static bool pnfs_within_mdsthreshold(struct nfs_open_context *ctx,
}

/* stop waiting if someone clears NFS_LAYOUT_RETRY_LAYOUTGET bit. */
static int pnfs_layoutget_retry_bit_wait(struct wait_bit_key *key)
static int pnfs_layoutget_retry_bit_wait(struct wait_bit_key *key, int mode)
{
if (!test_bit(NFS_LAYOUT_RETRY_LAYOUTGET, key->flags))
return 1;
return nfs_wait_bit_killable(key);
return nfs_wait_bit_killable(key, mode);
}

static bool pnfs_prepare_to_retry_layoutget(struct pnfs_layout_hdr *lo)
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10 changes: 5 additions & 5 deletions include/linux/wait.h
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Original file line number Diff line number Diff line change
Expand Up @@ -145,7 +145,7 @@ __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old)
list_del(&old->task_list);
}

typedef int wait_bit_action_f(struct wait_bit_key *);
typedef int wait_bit_action_f(struct wait_bit_key *, int mode);
void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
Expand Down Expand Up @@ -960,10 +960,10 @@ int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key);
} while (0)


extern int bit_wait(struct wait_bit_key *);
extern int bit_wait_io(struct wait_bit_key *);
extern int bit_wait_timeout(struct wait_bit_key *);
extern int bit_wait_io_timeout(struct wait_bit_key *);
extern int bit_wait(struct wait_bit_key *, int);
extern int bit_wait_io(struct wait_bit_key *, int);
extern int bit_wait_timeout(struct wait_bit_key *, int);
extern int bit_wait_io_timeout(struct wait_bit_key *, int);

/**
* wait_on_bit - wait for a bit to be cleared
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20 changes: 10 additions & 10 deletions kernel/sched/wait.c
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Original file line number Diff line number Diff line change
Expand Up @@ -392,7 +392,7 @@ __wait_on_bit(wait_queue_head_t *wq, struct wait_bit_queue *q,
do {
prepare_to_wait(wq, &q->wait, mode);
if (test_bit(q->key.bit_nr, q->key.flags))
ret = (*action)(&q->key);
ret = (*action)(&q->key, mode);
} while (test_bit(q->key.bit_nr, q->key.flags) && !ret);
finish_wait(wq, &q->wait);
return ret;
Expand Down Expand Up @@ -431,7 +431,7 @@ __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,
prepare_to_wait_exclusive(wq, &q->wait, mode);
if (!test_bit(q->key.bit_nr, q->key.flags))
continue;
ret = action(&q->key);
ret = action(&q->key, mode);
if (!ret)
continue;
abort_exclusive_wait(wq, &q->wait, mode, &q->key);
Expand Down Expand Up @@ -581,43 +581,43 @@ void wake_up_atomic_t(atomic_t *p)
}
EXPORT_SYMBOL(wake_up_atomic_t);

__sched int bit_wait(struct wait_bit_key *word)
__sched int bit_wait(struct wait_bit_key *word, int mode)
{
schedule();
if (signal_pending(current))
if (signal_pending_state(mode, current))
return -EINTR;
return 0;
}
EXPORT_SYMBOL(bit_wait);

__sched int bit_wait_io(struct wait_bit_key *word)
__sched int bit_wait_io(struct wait_bit_key *word, int mode)
{
io_schedule();
if (signal_pending(current))
if (signal_pending_state(mode, current))
return -EINTR;
return 0;
}
EXPORT_SYMBOL(bit_wait_io);

__sched int bit_wait_timeout(struct wait_bit_key *word)
__sched int bit_wait_timeout(struct wait_bit_key *word, int mode)
{
unsigned long now = READ_ONCE(jiffies);
if (time_after_eq(now, word->timeout))
return -EAGAIN;
schedule_timeout(word->timeout - now);
if (signal_pending(current))
if (signal_pending_state(mode, current))
return -EINTR;
return 0;
}
EXPORT_SYMBOL_GPL(bit_wait_timeout);

__sched int bit_wait_io_timeout(struct wait_bit_key *word)
__sched int bit_wait_io_timeout(struct wait_bit_key *word, int mode)
{
unsigned long now = READ_ONCE(jiffies);
if (time_after_eq(now, word->timeout))
return -EAGAIN;
io_schedule_timeout(word->timeout - now);
if (signal_pending(current))
if (signal_pending_state(mode, current))
return -EINTR;
return 0;
}
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6 changes: 3 additions & 3 deletions net/sunrpc/sched.c
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Original file line number Diff line number Diff line change
Expand Up @@ -250,11 +250,11 @@ void rpc_destroy_wait_queue(struct rpc_wait_queue *queue)
}
EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue);

static int rpc_wait_bit_killable(struct wait_bit_key *key)
static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode)
{
if (fatal_signal_pending(current))
return -ERESTARTSYS;
freezable_schedule_unsafe();
if (signal_pending_state(mode, current))
return -ERESTARTSYS;
return 0;
}

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