linux-kernel - [PATCH] usb: avoid redundant allocation and free of memory

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Message-Id: <20190523115208.24674-1-houweitaoo@gmail.com>
Date:   Thu, 23 May 2019 19:52:08 +0800
From:   Weitao Hou <houweitaoo@...il.com>
To:     gregkh@...uxfoundation.org, oneukum@...e.com,
        stern@...land.harvard.edu, chunfeng.yun@...iatek.com,
        ebiederm@...ssion.com, bigeasy@...utronix.de, iamkeyur96@...il.com,
        keescook@...omium.org, houweitaoo@...il.com
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] usb: avoid redundant allocation and free of memory

If usb is not attached, it's unnessary to allocate, copy
and free memory

Signed-off-by: Weitao Hou <houweitaoo@...il.com>
---
 drivers/usb/core/devio.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index fa783531ee88..aa17dab6c4ea 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -2130,6 +2130,9 @@ static int proc_ioctl(struct usb_dev_state *ps, struct usbdevfs_ioctl *ctl)
 	if (ps->privileges_dropped)
 		return -EACCES;
 
+	if (!connected(ps))
+		return -ENODEV;
+
 	/* alloc buffer */
 	size = _IOC_SIZE(ctl->ioctl_code);
 	if (size > 0) {
@@ -2146,11 +2149,6 @@ static int proc_ioctl(struct usb_dev_state *ps, struct usbdevfs_ioctl *ctl)
 		}
 	}
 
-	if (!connected(ps)) {
-		kfree(buf);
-		return -ENODEV;
-	}
-
 	if (ps->dev->state != USB_STATE_CONFIGURED)
 		retval = -EHOSTUNREACH;
 	else if (!(intf = usb_ifnum_to_if(ps->dev, ctl->ifno)))
-- 
2.18.0