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authorDavid Decotigny <ddecotig@google.com>2022-01-26 02:11:20 -0800
committerMiquel Raynal <miquel.raynal@bootlin.com>2022-01-26 11:43:02 +0100
commitca6263a0c9503d98b5aef04ed9b0f3971c66ec4e (patch)
tree8e53a4c2079d158c2d2463699b7bdab3a29ddc37 /drivers/mtd/mtd_blkdevs.c
parent7f852ec58af6ce8d7c6fc799b82d45d76e4bd994 (diff)
mtd_blkdevs: avoid soft lockups with some mtd/spi devices
With some spi devices, the heavy cpu usage due to polling the spi registers may lead to netdev timeouts, RCU complaints, etc. This can be acute in the absence of CONFIG_PREEMPT. This patch allows to give enough breathing room to avoid those incorrectly detected netdev timeouts for example. Example splat on 5.10.92: [ 828.399306] rcu: INFO: rcu_sched self-detected stall on CPU ... [ 828.419245] Task dump for CPU 1: [ 828.422465] task:kworker/1:1H state:R running task on cpu 1 stack: 0 pid: 76 ppid: 2 flags:0x0000002a [ 828.433132] Workqueue: kblockd blk_mq_run_work_fn [ 828.437820] Call trace: ... [ 828.512267] spi_mem_exec_op+0x4d0/0xde0 [ 828.516184] spi_mem_dirmap_read+0x180/0x39c [ 828.520443] spi_nor_read_data+0x428/0x7e8 [ 828.524523] spi_nor_read+0x154/0x214 [ 828.528172] mtd_read_oob+0x440/0x714 [ 828.531815] mtd_read+0xac/0x120 [ 828.535030] mtdblock_readsect+0x178/0x230 [ 828.539102] mtd_blktrans_work+0x9fc/0xf28 [ 828.543177] mtd_queue_rq+0x1ac/0x2e4 [ 828.546827] blk_mq_dispatch_rq_list+0x2cc/0xa44 [ 828.551419] blk_mq_do_dispatch_sched+0xb0/0x7cc [ 828.556010] __blk_mq_sched_dispatch_requests+0x350/0x494 [ 828.561372] blk_mq_sched_dispatch_requests+0xac/0xe4 [ 828.566387] __blk_mq_run_hw_queue+0x130/0x254 [ 828.570806] blk_mq_run_work_fn+0x50/0x60 [ 828.574814] process_one_work+0x578/0xf1c [ 828.578814] worker_thread+0x5dc/0xea0 [ 828.582547] kthread+0x270/0x2d4 [ 828.585765] ret_from_fork+0x10/0x30 Signed-off-by: David Decotigny <ddecotig@google.com> Reviewed-by: Richard Weinberger <richard@nod.at> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> Link: https://lore.kernel.org/linux-mtd/20220126101120.676021-1-decot+git@google.com
Diffstat (limited to 'drivers/mtd/mtd_blkdevs.c')
-rw-r--r--drivers/mtd/mtd_blkdevs.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 243f28a3206b..64d2b093f114 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -158,6 +158,7 @@ static void mtd_blktrans_work(struct mtd_blktrans_dev *dev)
}
background_done = 0;
+ cond_resched();
spin_lock_irq(&dev->queue_lock);
}
}