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Subject[PATCH 7/8] scsi: hisi_sas: Fix phyup timeout on FPGA
Date
From: Qi Liu <liuqi115@huawei.com>

The OOB interrupt and phyup interrupt handlers may run out-of-order in
high CPU usage scenarios. Since the hisi_sas_phy.timer is added in
hisi_sas_phy_oob_ready() and disarmed in phy_up_v3_hw(), this
out-of-order execution will cause hisi_sas_phy.timer timeout to trigger.

To solve, protect hisi_sas_phy.timer and .attached with a lock, and ensure
that the timer won't be added after phyup handler completes.

Signed-off-by: Qi Liu <liuqi115@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
drivers/scsi/hisi_sas/hisi_sas_main.c | 18 +++++++++++++-----
drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 10 ++++++++--
2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index 0e14f90dbb1e..66e63a336770 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -909,10 +909,14 @@ void hisi_sas_phy_oob_ready(struct hisi_hba *hisi_hba, int phy_no)
{
struct hisi_sas_phy *phy = &hisi_hba->phy[phy_no];
struct device *dev = hisi_hba->dev;
+ unsigned long flags;

dev_dbg(dev, "phy%d OOB ready\n", phy_no);
- if (phy->phy_attached)
+ spin_lock_irqsave(&phy->lock, flags);
+ if (phy->phy_attached) {
+ spin_unlock_irqrestore(&phy->lock, flags);
return;
+ }

if (!timer_pending(&phy->timer)) {
if (phy->wait_phyup_cnt < HISI_SAS_WAIT_PHYUP_RETRIES) {
@@ -920,13 +924,17 @@ void hisi_sas_phy_oob_ready(struct hisi_hba *hisi_hba, int phy_no)
phy->timer.expires = jiffies +
HISI_SAS_WAIT_PHYUP_TIMEOUT;
add_timer(&phy->timer);
- } else {
- dev_warn(dev, "phy%d failed to come up %d times, giving up\n",
- phy_no, phy->wait_phyup_cnt);
- phy->wait_phyup_cnt = 0;
+ spin_unlock_irqrestore(&phy->lock, flags);
+ return;
}
+
+ dev_warn(dev, "phy%d failed to come up %d times, giving up\n",
+ phy_no, phy->wait_phyup_cnt);
+ phy->wait_phyup_cnt = 0;
}
+ spin_unlock_irqrestore(&phy->lock, flags);
}
+
EXPORT_SYMBOL_GPL(hisi_sas_phy_oob_ready);

static void hisi_sas_phy_init(struct hisi_hba *hisi_hba, int phy_no)
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
index 11a44d9dd9b2..0239e2b4b84f 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
@@ -1484,7 +1484,6 @@ static irqreturn_t phy_up_v3_hw(int phy_no, struct hisi_hba *hisi_hba)
struct asd_sas_phy *sas_phy = &phy->sas_phy;
struct device *dev = hisi_hba->dev;

- del_timer(&phy->timer);
hisi_sas_phy_write32(hisi_hba, phy_no, PHYCTRL_PHY_ENA_MSK, 1);

port_id = hisi_sas_read32(hisi_hba, PHY_PORT_NUM_MA);
@@ -1561,9 +1560,16 @@ static irqreturn_t phy_up_v3_hw(int phy_no, struct hisi_hba *hisi_hba)
}

phy->port_id = port_id;
- phy->phy_attached = 1;
+
hisi_sas_notify_phy_event(phy, HISI_PHYE_PHY_UP);
+
res = IRQ_HANDLED;
+
+ spin_lock(&phy->lock);
+ /* Delete timer and set phy_attached atomically */
+ del_timer(&phy->timer);
+ phy->phy_attached = 1;
+ spin_unlock(&phy->lock);
end:
if (phy->reset_completion)
complete(phy->reset_completion);
--
2.26.2
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