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sched/core: Remove 'task' parameter and rename tsk_restore_flags() to current_restore_flags()

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It is not safe for one thread to modify the ->flags
of another thread as there is no locking that can protect
the update.

So tsk_restore_flags(), which takes a task pointer and modifies
the flags, is an invitation to do the wrong thing.

All current users pass "current" as the task, so no developers have
accepted that invitation.  It would be best to ensure it remains
that way.

So rename tsk_restore_flags() to current_restore_flags() and don't
pass in a task_struct pointer.  Always operate on current->flags.

Signed-off-by: NeilBrown <neilb@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
NeilBrown 2017-04-07 10:03:26 +10:00 committed by Ingo Molnar
parent 36a4dfc378
commit 717a94b5fc
7 changed files with 9 additions and 9 deletions
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2
drivers/block/nbd.c
View File

@ -244,7 +244,7 @@ static int sock_xmit(struct nbd_device *nbd, int index, int send,
*sent += result;
} while (msg_data_left(&msg));
tsk_restore_flags(current, pflags, PF_MEMALLOC);
current_restore_flags(pflags, PF_MEMALLOC);
return result;
}

2
drivers/scsi/iscsi_tcp.c
View File

@ -387,7 +387,7 @@ static int iscsi_sw_tcp_pdu_xmit(struct iscsi_task *task)
rc = 0;
}
tsk_restore_flags(current, pflags, PF_MEMALLOC);
current_restore_flags(pflags, PF_MEMALLOC);
return rc;
}

2
fs/nfsd/vfs.c
View File

@ -1004,7 +1004,7 @@ out_nfserr:
else
err = nfserrno(host_err);
if (test_bit(RQ_LOCAL, &rqstp->rq_flags))
tsk_restore_flags(current, pflags, PF_LESS_THROTTLE);
current_restore_flags(pflags, PF_LESS_THROTTLE);
return err;
}

6
include/linux/sched.h
View File

@ -1286,10 +1286,10 @@ TASK_PFA_TEST(LMK_WAITING, lmk_waiting)
TASK_PFA_SET(LMK_WAITING, lmk_waiting)
static inline void
tsk_restore_flags(struct task_struct *task, unsigned long orig_flags, unsigned long flags)
current_restore_flags(unsigned long orig_flags, unsigned long flags)
{
task->flags &= ~flags;
task->flags |= orig_flags & flags;
current->flags &= ~flags;
current->flags |= orig_flags & flags;
}
extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);

2
kernel/softirq.c
View File

@ -309,7 +309,7 @@ restart:
account_irq_exit_time(current);
__local_bh_enable(SOFTIRQ_OFFSET);
WARN_ON_ONCE(in_interrupt());
tsk_restore_flags(current, old_flags, PF_MEMALLOC);
current_restore_flags(old_flags, PF_MEMALLOC);
}
asmlinkage __visible void do_softirq(void)

2
net/core/dev.c
View File

@ -4240,7 +4240,7 @@ static int __netif_receive_skb(struct sk_buff *skb)
*/
current->flags |= PF_MEMALLOC;
ret = __netif_receive_skb_core(skb, true);
tsk_restore_flags(current, pflags, PF_MEMALLOC);
current_restore_flags(pflags, PF_MEMALLOC);
} else
ret = __netif_receive_skb_core(skb, false);

2
net/core/sock.c
View File

@ -325,7 +325,7 @@ int __sk_backlog_rcv(struct sock *sk, struct sk_buff *skb)
current->flags |= PF_MEMALLOC;
ret = sk->sk_backlog_rcv(sk, skb);
tsk_restore_flags(current, pflags, PF_MEMALLOC);
current_restore_flags(pflags, PF_MEMALLOC);
return ret;
}