All of lore.kernel.org
 help / color / mirror / Atom feed
From: Johan Hovold <johan@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org, Johan Hovold <johan@kernel.org>
Subject: [PATCH 3/4] USB: usblcd: drop redundant lcd mutex
Date: Thu, 26 Sep 2019 11:12:27 +0200	[thread overview]
Message-ID: <20190926091228.24634-9-johan@kernel.org> (raw)
In-Reply-To: <20190926091228.24634-1-johan@kernel.org>

Drop the redundant lcd mutex introduced by commit 925ce689bb31 ("USB:
autoconvert trivial BKL users to private mutex") which replaced an
earlier BKL use.

The lock serialised calls to open() against other open() and a custom
ioctl() returning the bcdDevice (sic!), but neither is needed.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/misc/usblcd.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/usb/misc/usblcd.c b/drivers/usb/misc/usblcd.c
index b898650a5570..732eb1f81368 100644
--- a/drivers/usb/misc/usblcd.c
+++ b/drivers/usb/misc/usblcd.c
@@ -30,7 +30,6 @@
 #define IOCTL_GET_DRV_VERSION	2
 
 
-static DEFINE_MUTEX(lcd_mutex);
 static const struct usb_device_id id_table[] = {
 	{ .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
 	{ },
@@ -81,12 +80,10 @@ static int lcd_open(struct inode *inode, struct file *file)
 	struct usb_interface *interface;
 	int subminor, r;
 
-	mutex_lock(&lcd_mutex);
 	subminor = iminor(inode);
 
 	interface = usb_find_interface(&lcd_driver, subminor);
 	if (!interface) {
-		mutex_unlock(&lcd_mutex);
 		printk(KERN_ERR "USBLCD: %s - error, can't find device for minor %d\n",
 		       __func__, subminor);
 		return -ENODEV;
@@ -101,13 +98,11 @@ static int lcd_open(struct inode *inode, struct file *file)
 	r = usb_autopm_get_interface(interface);
 	if (r < 0) {
 		kref_put(&dev->kref, lcd_delete);
-		mutex_unlock(&lcd_mutex);
 		return r;
 	}
 
 	/* save our object in the file's private structure */
 	file->private_data = dev;
-	mutex_unlock(&lcd_mutex);
 
 	return 0;
 }
@@ -176,14 +171,12 @@ static long lcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 	switch (cmd) {
 	case IOCTL_GET_HARD_VERSION:
-		mutex_lock(&lcd_mutex);
 		bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
 		sprintf(buf, "%1d%1d.%1d%1d",
 			(bcdDevice & 0xF000)>>12,
 			(bcdDevice & 0xF00)>>8,
 			(bcdDevice & 0xF0)>>4,
 			(bcdDevice & 0xF));
-		mutex_unlock(&lcd_mutex);
 		if (copy_to_user((void __user *)arg, buf, strlen(buf)) != 0)
 			return -EFAULT;
 		break;
-- 
2.23.0


  parent reply	other threads:[~2019-09-26  9:12 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-26  9:12 [PATCH 0/4] USB: usblcd: disconnect fix and locking clean ups Johan Hovold
2019-09-26  9:12 ` [PATCH 1/4] USB: usblcd: fix I/O after disconnect Johan Hovold
2019-09-26  9:12 ` [PATCH 2/4] USB: usblcd: drop redundant disconnect mutex Johan Hovold
2019-09-26  9:12 ` [PATCH 3/4] USB: usblcd: drop redundant lcd mutex Johan Hovold
2019-09-26  9:12 ` [PATCH 4/4] USB: usblcd: use pr_err() Johan Hovold
2019-09-26  9:12 ` [PATCH 0/4] USB: usblcd: disconnect fix and locking clean ups Johan Hovold
2019-09-26  9:17   ` Johan Hovold
2019-09-26  9:12 ` [PATCH 1/4] USB: usblcd: fix I/O after disconnect Johan Hovold
2019-09-26  9:12 ` [PATCH 2/4] USB: usblcd: drop redundant disconnect mutex Johan Hovold
2019-09-26  9:12 ` Johan Hovold [this message]
2019-09-26  9:12 ` [PATCH 4/4] USB: usblcd: use pr_err() Johan Hovold

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190926091228.24634-9-johan@kernel.org \
    --to=johan@kernel.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=linux-usb@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.