linux-kernel - [PATCH 4.19 321/421] PCI: aardvark: Dont rely on jiffies while holding spinlock

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Date:   Mon, 19 Jul 2021 16:52:12 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Remi Pommarel <repk@...plefau.lt>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <andrew.murray@....com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: [PATCH 4.19 321/421] PCI: aardvark: Dont rely on jiffies while holding spinlock

From: Remi Pommarel <repk@...plefau.lt>

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 <repk@...plefau.lt>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Reviewed-by: Andrew Murray <andrew.murray@....com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/pci/controller/pci-aardvark.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/pci/controller/pci-aardvark.c
+++ b/drivers/pci/controller/pci-aardvark.c
@@ -166,7 +166,8 @@
 	(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
@@ -369,17 +370,16 @@ static void advk_pcie_check_pio_status(s
 static int advk_pcie_wait_pio(struct advk_pcie *pcie)
 {
 	struct device *dev = &pcie->pdev->dev;
-	unsigned long timeout;
+	int i;
 
-	timeout = jiffies + msecs_to_jiffies(PIO_TIMEOUT_MS);
-
-	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");