linux-kernel - drivers/dma/idxd/device.c:370 idxd_cmd_exec() warn: mixing irqsave and irq

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Message-ID: <0047f184-52c2-4d7c-8f03-425b6f185860@stanley.mountain>
Date: Thu, 5 Dec 2024 10:53:29 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: oe-kbuild@...ts.linux.dev, Dave Jiang <dave.jiang@...el.com>
Cc: lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
	linux-kernel@...r.kernel.org, Vinod Koul <vkoul@...nel.org>,
	Tony Luck <tony.luck@...el.com>,
	Dan Williams <dan.j.williams@...el.com>
Subject: drivers/dma/idxd/device.c:370 idxd_cmd_exec() warn: mixing irqsave
 and irq

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   feffde684ac29a3b7aec82d2df850fbdbdee55e4
commit: 0d5c10b4c84d6ae6255129e5f16a0d2119c74334 dmaengine: idxd: add work queue drain support
config: x86_64-randconfig-161-20241112 (https://download.01.org/0day-ci/archive/20241205/202412050237.MXIHJMPC-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
| Closes: https://lore.kernel.org/r/202412050237.MXIHJMPC-lkp@intel.com/

smatch warnings:
drivers/dma/idxd/device.c:370 idxd_cmd_exec() warn: mixing irqsave and irq

vim +370 drivers/dma/idxd/device.c

0d5c10b4c84d6a Dave Jiang 2020-06-26  357  static void idxd_cmd_exec(struct idxd_device *idxd, int cmd_code, u32 operand,
0d5c10b4c84d6a Dave Jiang 2020-06-26  358  			  u32 *status)
bfe1d56091c1a4 Dave Jiang 2020-01-21  359  {
bfe1d56091c1a4 Dave Jiang 2020-01-21  360  	union idxd_command_reg cmd;
0d5c10b4c84d6a Dave Jiang 2020-06-26  361  	DECLARE_COMPLETION_ONSTACK(done);
0d5c10b4c84d6a Dave Jiang 2020-06-26  362  	unsigned long flags;
bfe1d56091c1a4 Dave Jiang 2020-01-21  363  
bfe1d56091c1a4 Dave Jiang 2020-01-21  364  	memset(&cmd, 0, sizeof(cmd));
bfe1d56091c1a4 Dave Jiang 2020-01-21  365  	cmd.cmd = cmd_code;
bfe1d56091c1a4 Dave Jiang 2020-01-21  366  	cmd.operand = operand;
0d5c10b4c84d6a Dave Jiang 2020-06-26  367  	cmd.int_req = 1;
0d5c10b4c84d6a Dave Jiang 2020-06-26  368  
0d5c10b4c84d6a Dave Jiang 2020-06-26  369  	spin_lock_irqsave(&idxd->dev_lock, flags);
0d5c10b4c84d6a Dave Jiang 2020-06-26 @370  	wait_event_lock_irq(idxd->cmd_waitq,
0d5c10b4c84d6a Dave Jiang 2020-06-26  371  			    !test_bit(IDXD_FLAG_CMD_RUNNING, &idxd->flags),
0d5c10b4c84d6a Dave Jiang 2020-06-26  372  			    idxd->dev_lock);

Please understand that these emails complaining about ancient code are
from the zero day bot, not from me.  The issue here is that
using spin_lock_irqsave() implies that perhaps the caller disabled IRQs
but then the wait_event_lock_irq() macro enables IRQs when it is
finished.

0d5c10b4c84d6a Dave Jiang 2020-06-26  373  
bfe1d56091c1a4 Dave Jiang 2020-01-21  374  	dev_dbg(&idxd->pdev->dev, "%s: sending cmd: %#x op: %#x\n",
bfe1d56091c1a4 Dave Jiang 2020-01-21  375  		__func__, cmd_code, operand);
0d5c10b4c84d6a Dave Jiang 2020-06-26  376  
0d5c10b4c84d6a Dave Jiang 2020-06-26  377  	__set_bit(IDXD_FLAG_CMD_RUNNING, &idxd->flags);
0d5c10b4c84d6a Dave Jiang 2020-06-26  378  	idxd->cmd_done = &done;
bfe1d56091c1a4 Dave Jiang 2020-01-21  379  	iowrite32(cmd.bits, idxd->reg_base + IDXD_CMD_OFFSET);
bfe1d56091c1a4 Dave Jiang 2020-01-21  380  
0d5c10b4c84d6a Dave Jiang 2020-06-26  381  	/*
0d5c10b4c84d6a Dave Jiang 2020-06-26  382  	 * After command submitted, release lock and go to sleep until
0d5c10b4c84d6a Dave Jiang 2020-06-26  383  	 * the command completes via interrupt.
0d5c10b4c84d6a Dave Jiang 2020-06-26  384  	 */
0d5c10b4c84d6a Dave Jiang 2020-06-26  385  	spin_unlock_irqrestore(&idxd->dev_lock, flags);

This irqrestore sets the IRQs back to whatever they were when the function
was called.

0d5c10b4c84d6a Dave Jiang 2020-06-26  386  	wait_for_completion(&done);
0d5c10b4c84d6a Dave Jiang 2020-06-26  387  	spin_lock_irqsave(&idxd->dev_lock, flags);
0d5c10b4c84d6a Dave Jiang 2020-06-26  388  	if (status)
0d5c10b4c84d6a Dave Jiang 2020-06-26  389  		*status = ioread32(idxd->reg_base + IDXD_CMDSTS_OFFSET);
0d5c10b4c84d6a Dave Jiang 2020-06-26  390  	__clear_bit(IDXD_FLAG_CMD_RUNNING, &idxd->flags);
0d5c10b4c84d6a Dave Jiang 2020-06-26  391  	/* Wake up other pending commands */
0d5c10b4c84d6a Dave Jiang 2020-06-26  392  	wake_up(&idxd->cmd_waitq);
0d5c10b4c84d6a Dave Jiang 2020-06-26  393  	spin_unlock_irqrestore(&idxd->dev_lock, flags);
bfe1d56091c1a4 Dave Jiang 2020-01-21  394  }

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki