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git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git
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Sebastian Andrzej Siewior
ecefbc09e8
Softirq is preemptible on PREEMPT_RT. Without a per-CPU lock in local_bh_disable() there is no guarantee that only one device is transmitting at a time. With preemption and multiple senders it is possible that the per-CPU `recursion' counter gets incremented by different threads and exceeds XMIT_RECURSION_LIMIT leading to a false positive recursion alert. The `more' member is subject to similar problems if set by one thread for one driver and wrongly used by another driver within another thread. Instead of adding a lock to protect the per-CPU variable it is simpler to make xmit per-task. Sending and receiving skbs happens always in thread context anyway. Having a lock to protected the per-CPU counter would block/ serialize two sending threads needlessly. It would also require a recursive lock to ensure that the owner can increment the counter further. Make the softnet_data.xmit a task_struct member on PREEMPT_RT. Add needed wrapper. Cc: Ben Segall <[email protected]> Cc: Daniel Bristot de Oliveira <[email protected]> Cc: Dietmar Eggemann <[email protected]> Cc: Juri Lelli <[email protected]> Cc: Mel Gorman <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Valentin Schneider <[email protected]> Cc: Vincent Guittot <[email protected]> Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jakub Kicinski <[email protected]>
14 lines
223 B
C
14 lines
223 B
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _LINUX_NETDEVICE_XMIT_H
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#define _LINUX_NETDEVICE_XMIT_H
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struct netdev_xmit {
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u16 recursion;
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u8 more;
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#ifdef CONFIG_NET_EGRESS
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u8 skip_txqueue;
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#endif
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};
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#endif
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