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Date: Thu, 29 Aug 2013 10:00:37 +0800
From: Vaughan Cao <vaughan.cao@...cle.com>
To: James.Bottomley@...senPartnership.com
Cc: joern@...fs.org, vaughan.cao@...cle.com, dgilbert@...erlog.com,
JBottomley@...allels.com, linux-scsi@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v7 2/4] sg: no need sg_open_exclusive_lock
Open exclusive check is protected by o_sem, no need sg_open_exclusive_lock.
@exclude is used to record which type of rwsem we are holding.
Signed-off-by: Vaughan Cao <vaughan.cao@...cle.com>
---
drivers/scsi/sg.c | 34 +++++-----------------------------
1 file changed, 5 insertions(+), 29 deletions(-)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 4efa9b5..d4af132 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -105,8 +105,6 @@ 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_SPINLOCK(sg_open_exclusive_lock);
-
static DEFINE_IDR(sg_index_idr);
static DEFINE_RWLOCK(sg_index_lock); /* Also used to lock
file descriptor list for device */
@@ -176,7 +174,6 @@ typedef struct sg_device { /* holds the state of each scsi generic device */
struct list_head sfds;
struct rw_semaphore o_sem; /* exclude open should hold this rwsem */
volatile char detached; /* 0->attached, 1->detached pending removal */
- /* exclude protected by sg_open_exclusive_lock */
char exclude; /* opened for exclusive access */
char sgdebug; /* 0->off, 1->sense, 9->dump dev, 10-> all devs */
struct gendisk *disk;
@@ -225,27 +222,6 @@ static int sg_allow_access(struct file *filp, unsigned char *cmd)
return blk_verify_command(cmd, filp->f_mode & FMODE_WRITE);
}
-static int get_exclude(Sg_device *sdp)
-{
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&sg_open_exclusive_lock, flags);
- ret = sdp->exclude;
- spin_unlock_irqrestore(&sg_open_exclusive_lock, flags);
- return ret;
-}
-
-static int set_exclude(Sg_device *sdp, char val)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&sg_open_exclusive_lock, flags);
- sdp->exclude = val;
- spin_unlock_irqrestore(&sg_open_exclusive_lock, flags);
- return val;
-}
-
static int sfds_list_empty(Sg_device *sdp)
{
unsigned long flags;
@@ -317,7 +293,7 @@ sg_open(struct inode *inode, struct file *filp)
}
/* Since write lock is held, no need to check sfd_list */
if (flags & O_EXCL)
- set_exclude(sdp, 1);
+ sdp->exclude = 1; /* used by release lock */
if (sdp->detached) {
retval = -ENODEV;
@@ -337,7 +313,7 @@ sg_open(struct inode *inode, struct file *filp)
retval = -ENOMEM;
sem_out:
if (flags & O_EXCL) {
- set_exclude(sdp, 0); /* undo if error */
+ sdp->exclude = 0; /* undo if error */
up_write(&sdp->o_sem);
} else
up_read(&sdp->o_sem);
@@ -364,8 +340,8 @@ sg_release(struct inode *inode, struct file *filp)
return -ENXIO;
SCSI_LOG_TIMEOUT(3, printk("sg_release: %s\n", sdp->disk->disk_name));
- excl = get_exclude(sdp);
- set_exclude(sdp, 0);
+ excl = sdp->exclude;
+ sdp->exclude = 0;
if (excl)
up_write(&sdp->o_sem);
else
@@ -2622,7 +2598,7 @@ static int sg_proc_seq_show_debug(struct seq_file *s, void *v)
scsidp->lun,
scsidp->host->hostt->emulated);
seq_printf(s, " sg_tablesize=%d excl=%d\n",
- sdp->sg_tablesize, get_exclude(sdp));
+ sdp->sg_tablesize, sdp->exclude);
sg_proc_debug_helper(s, sdp);
}
read_unlock_irqrestore(&sg_index_lock, iflags);
--
1.8.3.1
--
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