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PCI: aardvark: Don't rely on jiffies while holding spinlock

PATCH In review Pali Rohár 2 participants 2 messages Jul 16, 2021 – Jul 19, 2021 Stable branch

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Pali Rohár

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PATCH 1/1 PCI: aardvark: Don't rely on jiffies while holding spinlock

From: Remi Pommarel <[email protected]>

commit 7fbcb5da811be7d47468417c7795405058abb3da upstream.

advk_pcie_wait_pio() can be called while holding a spinlock (from pci_bus_read_config_dword()), then depends on jiffies in order to timeout while polling on PIO state registers. In the case the PIO transaction failed, the timeout will never happen and will also cause the cpu to stall.

This decrements a variable and wait instead of using jiffies.

Signed-off-by Remi Pommarel <[email protected]>
Signed-off-by Lorenzo Pieralisi <[email protected]>
Reviewed-by Andrew Murray <[email protected]>
Acked-by Thomas Petazzoni <[email protected]>

---
This is backport to 4.14 kernel. Backport of upstream commit can be done automatically by git cherry-pick command if merge.renamelimit variable is set to at least 12711.

---
 drivers/pci/host/pci-aardvark.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
drivers/pci/host/pci-aardvark.c +5 -5
index c1db09fbbe04..5dbbf3d7de36 100644
@@ -185,7 +185,8 @@
 	(PCIE_CONF_BUS(bus) | PCIE_CONF_DEV(PCI_SLOT(devfn))	| \
 	 PCIE_CONF_FUNC(PCI_FUNC(devfn)) | PCIE_CONF_REG(where))
 
-#define PIO_TIMEOUT_MS			1
+#define PIO_RETRY_CNT			500
+#define PIO_RETRY_DELAY			2 /* 2 us*/
 
 #define LINK_WAIT_MAX_RETRIES		10
 #define LINK_WAIT_USLEEP_MIN		90000

@@ -413,17 +414,16 @@ static void advk_pcie_check_pio_status(struct advk_pcie *pcie)
 static int advk_pcie_wait_pio(struct advk_pcie *pcie)
 {
 	struct device *dev = &pcie->pdev->dev;
-	unsigned long timeout;
-
-	timeout = jiffies + msecs_to_jiffies(PIO_TIMEOUT_MS);
+	int i;
 
-	while (time_before(jiffies, timeout)) {
+	for (i = 0; i < PIO_RETRY_CNT; i++) {
 		u32 start, isr;
 
 		start = advk_readl(pcie, PIO_START);
 		isr = advk_readl(pcie, PIO_ISR);
 		if (!start && isr)
 			return 0;
+		udelay(PIO_RETRY_DELAY);
 	}
 
 	dev_err(dev, "config read/write timed out\n");
Signature · 1 line
2.20.1
#1 lore raw
Quoted 16 lines · Pali Rohár

From: Remi Pommarel <[email protected]>

commit 7fbcb5da811be7d47468417c7795405058abb3da upstream.

advk_pcie_wait_pio() can be called while holding a spinlock (from pci_bus_read_config_dword()), then depends on jiffies in order to timeout while polling on PIO state registers. In the case the PIO transaction failed, the timeout will never happen and will also cause the cpu to stall.

This decrements a variable and wait instead of using jiffies.

Signed-off-by Remi Pommarel <[email protected]>
Signed-off-by Lorenzo Pieralisi <[email protected]>
Reviewed-by Andrew Murray <[email protected]>
Acked-by Thomas Petazzoni <[email protected]>
Quoted 7 lines

---
This is backport to 4.14 kernel. Backport of upstream commit can be done automatically by git cherry-pick command if merge.renamelimit variable is set to at least 12711.

---
 drivers/pci/host/pci-aardvark.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Also queued up to 4.19, thanks.

greg k-h