Commit 2acd76e7 authored by Bart Van Assche's avatar Bart Van Assche Committed by Martin K. Petersen
Browse files

scsi: ufs: Fix a race between the interrupt handler and the reset handler 

Prevent that both the interrupt handler and the reset handler try to
complete a request at the same time. This patch is the result of an
analysis of the following crash:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000120
CPU: 0 PID: 0 Comm: swapper/0 Tainted: G           OE     5.10.107-android13-4-00051-g1e48e8970cca-ab8664745 #1
pc : ufshcd_release_scsi_cmd+0x30/0x46c
lr : __ufshcd_transfer_req_compl+0x4fc/0x9c0
Call trace:
 ufshcd_release_scsi_cmd+0x30/0x46c
 __ufshcd_transfer_req_compl+0x4fc/0x9c0
 ufshcd_poll+0xf0/0x208
 ufshcd_sl_intr+0xb8/0xf0
 ufshcd_intr+0x168/0x2f4
 __handle_irq_event_percpu+0xa0/0x30c
 handle_irq_event+0x84/0x178
 handle_fasteoi_irq+0x150/0x2e8
 __handle_domain_irq+0x114/0x1e4
 gic_handle_irq.31846+0x58/0x300
 el1_irq+0xe4/0x1c0
 cpuidle_enter_state+0x3ac/0x8c4
 do_idle+0x2fc/0x55c
 cpu_startup_entry+0x84/0x90
 kernel_init+0x0/0x310
 start_kernel+0x0/0x608
 start_kernel+0x4ec/0x608

Link: https://lore.kernel.org/r/20220613214442.212466-4-bvanassche@acm.org


Reviewed-by: default avatarStanley Chu <stanley.chu@mediatek.com>
Reviewed-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent d1a76446

drivers/ufs/core/ufshcd.c

+19 −9
Original line number Diff line number Diff line
@@ -6968,14 +6968,14 @@ int ufshcd_exec_raw_upiu_cmd(struct ufs_hba *hba, 
}



/**

 * ufshcd_eh_device_reset_handler - device reset handler registered to

 *                                    scsi layer.

 * ufshcd_eh_device_reset_handler() - Reset a single logical unit.

 * @cmd: SCSI command pointer

 *

 * Returns SUCCESS/FAILED

 */

static int ufshcd_eh_device_reset_handler(struct scsi_cmnd *cmd)

{

	unsigned long flags, pending_reqs = 0, not_cleared = 0;

	struct Scsi_Host *host;

	struct ufs_hba *hba;

	u32 pos;
@@ -6994,14 +6994,24 @@ static int ufshcd_eh_device_reset_handler(struct scsi_cmnd *cmd) 
	}



	/* clear the commands that were pending for corresponding LUN */

	for_each_set_bit(pos, &hba->outstanding_reqs, hba->nutrs) {

		if (hba->lrb[pos].lun == lun) {

			err = ufshcd_clear_cmds(hba, 1U << pos);

			if (err)

				break;

			__ufshcd_transfer_req_compl(hba, 1U << pos);

		}

	spin_lock_irqsave(&hba->outstanding_lock, flags);

	for_each_set_bit(pos, &hba->outstanding_reqs, hba->nutrs)

		if (hba->lrb[pos].lun == lun)

			__set_bit(pos, &pending_reqs);

	hba->outstanding_reqs &= ~pending_reqs;

	spin_unlock_irqrestore(&hba->outstanding_lock, flags);



	if (ufshcd_clear_cmds(hba, pending_reqs) < 0) {

		spin_lock_irqsave(&hba->outstanding_lock, flags);

		not_cleared = pending_reqs &

			ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);

		hba->outstanding_reqs |= not_cleared;

		spin_unlock_irqrestore(&hba->outstanding_lock, flags);



		dev_err(hba->dev, "%s: failed to clear requests %#lx\n",

			__func__, not_cleared);

	}

	__ufshcd_transfer_req_compl(hba, pending_reqs & ~not_cleared);



out:

	hba->req_abort_count = 0;