The 'reserved' page array is used as a short-cut for mapping
data, saving us to allocate pages per request.
However, the 'reserved' array is only capable of holding one
request, so this patch introduces a mutex for protect
'sg_fd' against concurrent accesses.
Signed-off-by: Hannes Reinecke <h...@suse.com>
Reviewed-by: Johannes Thumshirn <jthumsh...@suse.de>
Tested-by: Johannes Thumshirn <jthumsh...@suse.de>
---
drivers/scsi/sg.c | 45 +++++++++++++++++++++++++--------------------
1 file changed, 25 insertions(+), 20 deletions(-)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 92cc658..ddc1808 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -142,6 +142,7 @@
struct sg_device *parentdp; /* owning device */
wait_queue_head_t read_wait; /* queue read until command done */
rwlock_t rq_list_lock; /* protect access to list in req_arr */
+ struct mutex f_mutex; /* protect against changes in this fd */
int timeout; /* defaults to SG_DEFAULT_TIMEOUT */
int timeout_user; /* defaults to SG_DEFAULT_TIMEOUT_USER */
Sg_scatter_hold reserve; /* buffer held for this file descriptor
*/
@@ -153,6 +154,7 @@
unsigned char next_cmd_len; /* 0: automatic, >0: use on next write() */
char keep_orphan; /* 0 -> drop orphan (def), 1 -> keep for read()
*/
char mmap_called; /* 0 -> mmap() never called on this fd */
+ char res_in_use; /* 1 -> 'reserve' array in use */
struct kref f_ref;
struct execute_work ew;
} Sg_fd;
@@ -196,7 +198,6 @@ static int sg_common_write(Sg_fd * sfp, Sg_request * srp,
static Sg_request *sg_get_rq_mark(Sg_fd * sfp, int pack_id);
static Sg_request *sg_add_request(Sg_fd * sfp);
static int sg_remove_request(Sg_fd * sfp, Sg_request * srp);
-static int sg_res_in_use(Sg_fd * sfp);
static Sg_device *sg_get_dev(int dev);
static void sg_device_destroy(struct kref *kref);
@@ -612,6 +613,7 @@ static int sg_allow_access(struct file *filp, unsigned char
*cmd)
}
buf += SZ_SG_HEADER;
__get_user(opcode, buf);
+ mutex_lock(&sfp->f_mutex);
if (sfp->next_cmd_len > 0) {
cmd_size = sfp->next_cmd_len;
sfp->next_cmd_len = 0; /* reset so only this write() effected
*/
@@ -620,6 +622,7 @@ static int sg_allow_access(struct file *filp, unsigned char
*cmd)
if ((opcode >= 0xc0) && old_hdr.twelve_byte)
cmd_size = 12;
}
+ mutex_unlock(&sfp->f_mutex);
SCSI_LOG_TIMEOUT(4, sg_printk(KERN_INFO, sdp,
"sg_write: scsi opcode=0x%02x, cmd_size=%d\n", (int) opcode,
cmd_size));
/* Determine buffer size. */
@@ -719,7 +722,7 @@ static int sg_allow_access(struct file *filp, unsigned char
*cmd)
sg_remove_request(sfp, srp);
return -EINVAL; /* either MMAP_IO or DIRECT_IO (not
both) */
}
- if (sg_res_in_use(sfp)) {
+ if (sfp->res_in_use) {
sg_remove_request(sfp, srp);
return -EBUSY; /* reserve buffer already being used */
}
@@ -953,12 +956,18 @@ static int max_sectors_bytes(struct request_queue *q)
return -EINVAL;
val = min_t(int, val,
max_sectors_bytes(sdp->device->request_queue));
+ mutex_lock(&sfp->f_mutex);
if (val != sfp->reserve.bufflen) {
- if (sg_res_in_use(sfp) || sfp->mmap_called)
+ if (sfp->mmap_called ||
+ sfp->res_in_use) {
+ mutex_unlock(&sfp->f_mutex);
return -EBUSY;
+ }
+
sg_remove_scat(sfp, &sfp->reserve);
sg_build_reserve(sfp, val);
}
+ mutex_unlock(&sfp->f_mutex);
return 0;
case SG_GET_RESERVED_SIZE:
val = min_t(int, sfp->reserve.bufflen,
@@ -1718,13 +1727,22 @@ static long sg_compat_ioctl(struct file *filp, unsigned
int cmd_in, unsigned lon
md = &map_data;
if (md) {
- if (!sg_res_in_use(sfp) && dxfer_len <= rsv_schp->bufflen)
+ mutex_lock(&sfp->f_mutex);
+ if (dxfer_len <= rsv_schp->bufflen &&
+ !sfp->res_in_use) {
+ sfp->res_in_use = 1;
sg_link_reserve(sfp, srp, dxfer_len);
- else {
+ } else if ((hp->flags & SG_FLAG_MMAP_IO) && sfp->res_in_use) {
+ mutex_unlock(&sfp->f_mutex);
+ return -EBUSY;
+ } else {
res = sg_build_indirect(req_schp, sfp, dxfer_len);
- if (res)
+ if (res) {
+ mutex_unlock(&sfp->f_mutex);
return res;
+ }
}
+ mutex_unlock(&sfp->f_mutex);
md->pages = req_schp->pages;
md->page_order = req_schp->page_order;
@@ -2125,6 +2143,7 @@ static long sg_compat_ioctl(struct file *filp, unsigned
int cmd_in, unsigned lon
rwlock_init(&sfp->rq_list_lock);
kref_init(&sfp->f_ref);
+ mutex_init(&sfp->f_mutex);
sfp->timeout = SG_DEFAULT_TIMEOUT;
sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER;
sfp->force_packid = SG_DEF_FORCE_PACK_ID;
@@ -2198,20 +2217,6 @@ static long sg_compat_ioctl(struct file *filp, unsigned
int cmd_in, unsigned lon
schedule_work(&sfp->ew.work);
}
-static int
-sg_res_in_use(Sg_fd * sfp)
-{
- const Sg_request *srp;
- unsigned long iflags;
-
- read_lock_irqsave(&sfp->rq_list_lock, iflags);
- for (srp = sfp->headrp; srp; srp = srp->nextrp)
- if (srp->res_used)
- break;
- read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
- return srp ? 1 : 0;
-}
-
#ifdef CONFIG_SCSI_PROC_FS
static int
sg_idr_max_id(int id, void *p, void *data)
--
1.8.5.6
