linux-kernel - [PATCH 4.18 107/228] scsi: hisi_sas: Fix the conflict between dev gone and host reset

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Message-Id: <20181002132506.646709915@linuxfoundation.org>
Date:   Tue,  2 Oct 2018 06:23:24 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xiaofei Tan <tanxiaofei@...wei.com>,
        John Garry <john.garry@...wei.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.18 107/228] scsi: hisi_sas: Fix the conflict between dev gone and host reset

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Xiaofei Tan <tanxiaofei@...wei.com>

[ Upstream commit d2fc401e47529d9ffd2673a5395d56002e31ad98 ]

There is a possible conflict when a device is removed and host reset occurs
concurrently.

The reason is that then the device is notified as gone, we try to clear the
ITCT, which is notified via an interrupt. The dev gone function pends on
this event with a completion, which is completed when the ITCT interrupt
occurs.

But host reset will disable all interrupts, the wait_for_completion() may
wait indefinitely.

This patch adds an semaphore to synchronise this two processes. The
semaphore is taken by the host reset as the basis of synchronising.

Signed-off-by: Xiaofei Tan <tanxiaofei@...wei.com>
Signed-off-by: John Garry <john.garry@...wei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/scsi/hisi_sas/hisi_sas.h      |    1 +
 drivers/scsi/hisi_sas/hisi_sas_main.c |    6 ++++++
 2 files changed, 7 insertions(+)

--- a/drivers/scsi/hisi_sas/hisi_sas.h
+++ b/drivers/scsi/hisi_sas/hisi_sas.h
@@ -277,6 +277,7 @@ struct hisi_hba {
 
 	int n_phy;
 	spinlock_t lock;
+	struct semaphore sem;
 
 	struct timer_list timer;
 	struct workqueue_struct *wq;
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -914,7 +914,9 @@ static void hisi_sas_dev_gone(struct dom
 
 		hisi_sas_dereg_device(hisi_hba, device);
 
+		down(&hisi_hba->sem);
 		hisi_hba->hw->clear_itct(hisi_hba, sas_dev);
+		up(&hisi_hba->sem);
 		device->lldd_dev = NULL;
 	}
 
@@ -1364,6 +1366,7 @@ static int hisi_sas_controller_reset(str
 	if (test_and_set_bit(HISI_SAS_RESET_BIT, &hisi_hba->flags))
 		return -1;
 
+	down(&hisi_hba->sem);
 	dev_info(dev, "controller resetting...\n");
 	old_state = hisi_hba->hw->get_phys_state(hisi_hba);
 
@@ -1378,6 +1381,7 @@ static int hisi_sas_controller_reset(str
 	if (rc) {
 		dev_warn(dev, "controller reset failed (%d)\n", rc);
 		clear_bit(HISI_SAS_REJECT_CMD_BIT, &hisi_hba->flags);
+		up(&hisi_hba->sem);
 		scsi_unblock_requests(shost);
 		goto out;
 	}
@@ -1388,6 +1392,7 @@ static int hisi_sas_controller_reset(str
 	hisi_hba->hw->phys_init(hisi_hba);
 	msleep(1000);
 	hisi_sas_refresh_port_id(hisi_hba);
+	up(&hisi_hba->sem);
 
 	if (hisi_hba->reject_stp_links_msk)
 		hisi_sas_terminate_stp_reject(hisi_hba);
@@ -2016,6 +2021,7 @@ int hisi_sas_alloc(struct hisi_hba *hisi
 	struct device *dev = hisi_hba->dev;
 	int i, s, max_command_entries = hisi_hba->hw->max_command_entries;
 
+	sema_init(&hisi_hba->sem, 1);
 	spin_lock_init(&hisi_hba->lock);
 	for (i = 0; i < hisi_hba->n_phy; i++) {
 		hisi_sas_phy_init(hisi_hba, i);