From 37b9d1e0017b2d8384ad03d250b15fd3d69771d5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?J=C3=B6rn=20Engel?= Date: Thu, 12 Apr 2012 17:35:05 -0400 Subject: [PATCH] [SCSI] sg: remove sg_mutex With the exception of the detached field, sg_mutex no longer adds any locking. detached handling has been broken before and is still broken and this patch does not seem to make things worse than they were to begin with. However, I have observed cases of tasks being blocked for >200s waiting for sg_mutex. So the removal clearly adds value for very little cost. Signed-off-by: Joern Engel Acked-by: Douglas Gilbert Signed-off-by: James Bottomley --- drivers/scsi/sg.c | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 53af8089dcb9..470d3a0b6098 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -104,7 +104,6 @@ static int scatter_elem_sz_prev = SG_SCATTER_SZ; static int sg_add(struct device *, struct class_interface *); static void sg_remove(struct device *, struct class_interface *); -static DEFINE_MUTEX(sg_mutex); static DEFINE_SPINLOCK(sg_open_exclusive_lock); static DEFINE_IDR(sg_index_idr); @@ -268,7 +267,6 @@ sg_open(struct inode *inode, struct file *filp) int res; int retval; - mutex_lock(&sg_mutex); nonseekable_open(inode, filp); SCSI_LOG_TIMEOUT(3, printk("sg_open: dev=%d, flags=0x%x\n", dev, flags)); sdp = sg_get_dev(dev); @@ -350,7 +348,6 @@ sdp_put: sg_put: if (sdp) sg_put_dev(sdp); - mutex_unlock(&sg_mutex); return retval; } @@ -808,7 +805,7 @@ static int srp_done(Sg_fd *sfp, Sg_request *srp) return ret; } -static int +static long sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg) { void __user *p = (void __user *)arg; @@ -1118,18 +1115,6 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg) } } -static long -sg_unlocked_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg) -{ - int ret; - - mutex_lock(&sg_mutex); - ret = sg_ioctl(filp, cmd_in, arg); - mutex_unlock(&sg_mutex); - - return ret; -} - #ifdef CONFIG_COMPAT static long sg_compat_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg) { @@ -1377,7 +1362,7 @@ static const struct file_operations sg_fops = { .read = sg_read, .write = sg_write, .poll = sg_poll, - .unlocked_ioctl = sg_unlocked_ioctl, + .unlocked_ioctl = sg_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = sg_compat_ioctl, #endif