usb: ehci: Prevent missed ehci interrupts with edge-triggered MSI

stable inclusion
from stable-5.10.54
commit c938e65768e0a80e7ea24899795878072e79b152
bugzilla: 175586 https://gitee.com/openeuler/kernel/issues/I4DVDU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c938e65768e0a80e7ea24899795878072e79b152

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

commit 0b605572 upstream.

When MSI is used by the ehci-hcd driver, it can cause lost interrupts which
results in EHCI only continuing to work due to a polling fallback. But the
reliance of polling drastically reduces performance of any I/O through EHCI.

Interrupts are lost as the EHCI interrupt handler does not safely handle
edge-triggered interrupts. It fails to ensure all interrupt status bits are
cleared, which works with level-triggered interrupts but not the
edge-triggered interrupts typical from using MSI.

To fix this problem, check if the driver may have raced with the hardware
setting additional interrupt status bits and clear status until it is in a
stable state.

Fixes: 306c54d0 ("usb: hcd: Try MSI interrupts on PCI devices")
Tested-by: NLaurence Oberman <loberman@redhat.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NDavid Jeffery <djeffery@redhat.com>
Link: https://lore.kernel.org/r/20210715213744.GA44506@redhat
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/usb/host/ehci-hcd.c

@@ -703,7 +703,8 @@ EXPORT_SYMBOL_GPL(ehci_setup);
 static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 {
 	struct ehci_hcd		*ehci = hcd_to_ehci (hcd);
-	u32			status, masked_status, pcd_status = 0, cmd;
+	u32			status, current_status, masked_status, pcd_status = 0;
+	u32			cmd;
 	int			bh;
 	unsigned long		flags;
 
@@ -715,19 +716,22 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 	 */
 	spin_lock_irqsave(&ehci->lock, flags);
 
-	status = ehci_readl(ehci, &ehci->regs->status);
+	status = 0;
+	current_status = ehci_readl(ehci, &ehci->regs->status);
+restart:
 
 	/* e.g. cardbus physical eject */
-	if (status == ~(u32) 0) {
+	if (current_status == ~(u32) 0) {
 		ehci_dbg (ehci, "device removed\n");
 		goto dead;
 	}
+	status |= current_status;
 
 	/*
 	 * We don't use STS_FLR, but some controllers don't like it to
 	 * remain on, so mask it out along with the other status bits.
 	 */
-	masked_status = status & (INTR_MASK | STS_FLR);
+	masked_status = current_status & (INTR_MASK | STS_FLR);
 
 	/* Shared IRQ? */
 	if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) {
@@ -737,6 +741,12 @@ static irqreturn_t ehci_irq (struct usb_hcd *hcd)
 
 	/* clear (just) interrupts */
 	ehci_writel(ehci, masked_status, &ehci->regs->status);
+
+	/* For edge interrupts, don't race with an interrupt bit being raised */
+	current_status = ehci_readl(ehci, &ehci->regs->status);
+	if (current_status & INTR_MASK)
+		goto restart;
+
 	cmd = ehci_readl(ehci, &ehci->regs->command);
 	bh = 0;