linux-kernel - [PATCH v15 08/50] xhci: Don't check if the event ring is valid before every event TRB

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Date: Mon, 12 Feb 2024 16:53:40 -0800
From: Wesley Cheng <quic_wcheng@...cinc.com>
To: <srinivas.kandagatla@...aro.org>, <mathias.nyman@...el.com>,
        <perex@...ex.cz>, <conor+dt@...nel.org>, <corbet@....net>,
        <lgirdwood@...il.com>, <andersson@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <gregkh@...uxfoundation.org>,
        <Thinh.Nguyen@...opsys.com>, <broonie@...nel.org>,
        <bgoswami@...cinc.com>, <tiwai@...e.com>, <robh+dt@...nel.org>,
        <konrad.dybcio@...aro.org>
CC: <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-sound@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <alsa-devel@...a-project.org>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Wesley Cheng <quic_wcheng@...cinc.com>
Subject: [PATCH v15 08/50] xhci: Don't check if the event ring is valid before every event TRB

From: Mathias Nyman <mathias.nyman@...ux.intel.com>

Check if the event ring exists and is valid once when the event handler
is called, not before every individual event TRB.

At this point the interrupter is valid, so no need to check that.

Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
---
 drivers/usb/host/xhci-ring.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 48388bc16b24..293239d8fab0 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2922,12 +2922,6 @@ static int xhci_handle_event(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
 	union xhci_trb *event;
 	u32 trb_type;
 
-	/* Event ring hasn't been allocated yet. */
-	if (!ir || !ir->event_ring || !ir->event_ring->dequeue) {
-		xhci_err(xhci, "ERROR interrupter not ready\n");
-		return -ENOMEM;
-	}
-
 	event = ir->event_ring->dequeue;
 
 	if (!unhandled_event_trb(ir->event_ring))
@@ -3031,6 +3025,12 @@ static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir
 
 	xhci_clear_interrupt_pending(xhci, ir);
 
+	/* Event ring hasn't been allocated yet. */
+	if (!ir->event_ring || !ir->event_ring->dequeue) {
+		xhci_err(xhci, "ERROR interrupter event ring not ready\n");
+		return -ENOMEM;
+	}
+
 	if (xhci->xhc_state & XHCI_STATE_DYING ||
 	    xhci->xhc_state & XHCI_STATE_HALTED) {
 		xhci_dbg(xhci, "xHCI dying, ignoring interrupt. Shouldn't IRQs be disabled?\n");