linux-kernel - [PATCH] usb: host: ehci-sched: add comment about find

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Date:   Sun, 11 Oct 2020 21:50:08 +0100
From:   Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:     Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-safety@...ts.elisa.tech,
        linux-usb@...r.kernel.org,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH] usb: host: ehci-sched: add comment about find_tt() not returning error

Add a comment explaining why find_tt() will not return error even though
find_tt() is checking for NULL and other errors.

Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
---
 drivers/usb/host/ehci-sched.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index 6dfb242f9a4b..0f85aa9b2fb1 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -244,6 +244,12 @@ static void reserve_release_intr_bandwidth(struct ehci_hcd *ehci,
 
 	/* FS/LS bus bandwidth */
 	if (tt_usecs) {
+		/*
+		 * find_tt() will not return any error here as we have
+		 * already called find_tt() before calling this function
+		 * and checked for any error return. The previous call
+		 * would have created the data structure.
+		 */
 		tt = find_tt(qh->ps.udev);
 		if (sign > 0)
 			list_add_tail(&qh->ps.ps_list, &tt->ps_list);
@@ -1337,6 +1343,12 @@ static void reserve_release_iso_bandwidth(struct ehci_hcd *ehci,
 			}
 		}
 
+		/*
+		 * find_tt() will not return any error here as we have
+		 * already called find_tt() before calling this function
+		 * and checked for any error return. The previous call
+		 * would have created the data structure.
+		 */
 		tt = find_tt(stream->ps.udev);
 		if (sign > 0)
 			list_add_tail(&stream->ps.ps_list, &tt->ps_list);
-- 
2.11.0