[PATCH] sg.c: update

The attachment combines the most recent patch from
Yum Rayan <yum.rayan@gmail.com> (to reduce sg stack
usage), Adrian Bunk <bunk@stusta.de> (to fix check
after use) and me (fix elapsed time calculation
(duration) on ia64 machines).

I have modified the patch from Yum Rayan so kmalloc()
in sg_read() is only called for the (rare) code paths
that need them.

Changelog:
   - reduce stack usage in sg_ioctl() and sg_read()
   - fix check after use in sg_mmap()
   - hold duration internally in milliseconds and
     check current time later than held time

Signed-off-by: Douglas Gilbert <dougg@torque.net>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

1 files changed, 132 insertions, 71 deletions

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index fd72d73bb244..32de9aabcb99 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -18,8 +18,8 @@
  *
  */
 
-static int sg_version_num = 30532;      /* 2 digits for each component */
-#define SG_VERSION_STR "3.5.32"
+static int sg_version_num = 30533;      /* 2 digits for each component */
+#define SG_VERSION_STR "3.5.33"
 
 /*
  *  D. P. Gilbert (dgilbert@interlog.com, dougg@triode.net.au), notes:
@@ -60,7 +60,7 @@ static int sg_version_num = 30532;	/* 2 digits for each component */
 
 #ifdef CONFIG_SCSI_PROC_FS
 #include <linux/proc_fs.h>
-static char *sg_version_date = "20050117";
+static char *sg_version_date = "20050328";
 
 static int sg_proc_init(void);
 static void sg_proc_cleanup(void);
@@ -330,14 +330,13 @@ sg_release(struct inode *inode, struct file *filp)
 static ssize_t
 sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
 {
-        int res;
         Sg_device *sdp;
         Sg_fd *sfp;
         Sg_request *srp;
         int req_pack_id = -1;
-        struct sg_header old_hdr;
-        sg_io_hdr_t new_hdr;
         sg_io_hdr_t *hp;
+        struct sg_header *old_hdr = NULL;
+        int retval = 0;
 
         if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
                 return -ENXIO;
@@ -346,98 +345,138 @@ sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
         if (!access_ok(VERIFY_WRITE, buf, count))
                 return -EFAULT;
         if (sfp->force_packid && (count >= SZ_SG_HEADER)) {
-                if (__copy_from_user(&old_hdr, buf, SZ_SG_HEADER))
-                        return -EFAULT;
-                if (old_hdr.reply_len < 0) {
+                old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
+                if (!old_hdr)
+                        return -ENOMEM;
+                if (__copy_from_user(old_hdr, buf, SZ_SG_HEADER)) {
+                        retval = -EFAULT;
+                        goto free_old_hdr;
+                }
+                if (old_hdr->reply_len < 0) {
                         if (count >= SZ_SG_IO_HDR) {
-                                if (__copy_from_user
-                                    (&new_hdr, buf, SZ_SG_IO_HDR))
-                                        return -EFAULT;
-                                req_pack_id = new_hdr.pack_id;
+                                sg_io_hdr_t *new_hdr;
+                                new_hdr = kmalloc(SZ_SG_IO_HDR, GFP_KERNEL);
+                                if (!new_hdr) {
+                                        retval = -ENOMEM;
+                                        goto free_old_hdr;
+                                }
+                                retval =__copy_from_user
+                                    (new_hdr, buf, SZ_SG_IO_HDR);
+                                req_pack_id = new_hdr->pack_id;
+                                kfree(new_hdr);
+                                if (retval) {
+                                        retval = -EFAULT;
+                                        goto free_old_hdr;
+                                }
                         }
                 } else
-                        req_pack_id = old_hdr.pack_id;
+                        req_pack_id = old_hdr->pack_id;
         }
         srp = sg_get_rq_mark(sfp, req_pack_id);
         if (!srp) {             /* now wait on packet to arrive */
-                if (sdp->detached)
-                        return -ENODEV;
-                if (filp->f_flags & O_NONBLOCK)
-                        return -EAGAIN;
+                if (sdp->detached) {
+                        retval = -ENODEV;
+                        goto free_old_hdr;
+                }
+                if (filp->f_flags & O_NONBLOCK) {
+                        retval = -EAGAIN;
+                        goto free_old_hdr;
+                }
                 while (1) {
-                        res = 0;        /* following is a macro that beats race condition */
+                        retval = 0; /* following macro beats race condition */
                         __wait_event_interruptible(sfp->read_wait,
-                                (sdp->detached || (srp = sg_get_rq_mark(sfp, req_pack_id))), 
-                                                   res);
-                        if (sdp->detached)
-                                return -ENODEV;
-                        if (0 == res)
+                                (sdp->detached ||
+                                (srp = sg_get_rq_mark(sfp, req_pack_id))), 
+                                retval);
+                        if (sdp->detached) {
+                                retval = -ENODEV;
+                                goto free_old_hdr;
+                        }
+                        if (0 == retval)
                                 break;
-                        return res;     /* -ERESTARTSYS because signal hit process */
+
+                        /* -ERESTARTSYS as signal hit process */
+                        goto free_old_hdr;
                 }
         }
-        if (srp->header.interface_id != '\0')
-                return sg_new_read(sfp, buf, count, srp);
+        if (srp->header.interface_id != '\0') {
+                retval = sg_new_read(sfp, buf, count, srp);
+                goto free_old_hdr;
+        }
 
         hp = &srp->header;
-        memset(&old_hdr, 0, SZ_SG_HEADER);
-        old_hdr.reply_len = (int) hp->timeout;
-        old_hdr.pack_len = old_hdr.reply_len; /* very old, strange behaviour */
-        old_hdr.pack_id = hp->pack_id;
-        old_hdr.twelve_byte =
+        if (old_hdr == NULL) {
+                old_hdr = kmalloc(SZ_SG_HEADER, GFP_KERNEL);
+                if (! old_hdr) {
+                        retval = -ENOMEM;
+                        goto free_old_hdr;
+                }
+        }
+        memset(old_hdr, 0, SZ_SG_HEADER);
+        old_hdr->reply_len = (int) hp->timeout;
+        old_hdr->pack_len = old_hdr->reply_len; /* old, strange behaviour */
+        old_hdr->pack_id = hp->pack_id;
+        old_hdr->twelve_byte =
             ((srp->data.cmd_opcode >= 0xc0) && (12 == hp->cmd_len)) ? 1 : 0;
-        old_hdr.target_status = hp->masked_status;
-        old_hdr.host_status = hp->host_status;
-        old_hdr.driver_status = hp->driver_status;
+        old_hdr->target_status = hp->masked_status;
+        old_hdr->host_status = hp->host_status;
+        old_hdr->driver_status = hp->driver_status;
         if ((CHECK_CONDITION & hp->masked_status) ||
             (DRIVER_SENSE & hp->driver_status))
-                memcpy(old_hdr.sense_buffer, srp->sense_b,
-                       sizeof (old_hdr.sense_buffer));
+                memcpy(old_hdr->sense_buffer, srp->sense_b,
+                       sizeof (old_hdr->sense_buffer));
         switch (hp->host_status) {
         /* This setup of 'result' is for backward compatibility and is best
            ignored by the user who should use target, host + driver status */
         case DID_OK:
         case DID_PASSTHROUGH:
         case DID_SOFT_ERROR:
-                old_hdr.result = 0;
+                old_hdr->result = 0;
                 break;
         case DID_NO_CONNECT:
         case DID_BUS_BUSY:
         case DID_TIME_OUT:
-                old_hdr.result = EBUSY;
+                old_hdr->result = EBUSY;
                 break;
         case DID_BAD_TARGET:
         case DID_ABORT:
         case DID_PARITY:
         case DID_RESET:
         case DID_BAD_INTR:
-                old_hdr.result = EIO;
+                old_hdr->result = EIO;
                 break;
         case DID_ERROR:
-                old_hdr.result = (srp->sense_b[0] == 0 && 
+                old_hdr->result = (srp->sense_b[0] == 0 && 
                                   hp->masked_status == GOOD) ? 0 : EIO;
                 break;
         default:
-                old_hdr.result = EIO;
+                old_hdr->result = EIO;
                 break;
         }
 
         /* Now copy the result back to the user buffer.  */
         if (count >= SZ_SG_HEADER) {
-                if (__copy_to_user(buf, &old_hdr, SZ_SG_HEADER))
-                        return -EFAULT;
+                if (__copy_to_user(buf, old_hdr, SZ_SG_HEADER)) {
+                        retval = -EFAULT;
+                        goto free_old_hdr;
+                }
                 buf += SZ_SG_HEADER;
-                if (count > old_hdr.reply_len)
-                        count = old_hdr.reply_len;
+                if (count > old_hdr->reply_len)
+                        count = old_hdr->reply_len;
                 if (count > SZ_SG_HEADER) {
-                        if ((res =
-                             sg_read_oxfer(srp, buf, count - SZ_SG_HEADER)))
-                                return -EFAULT;
+                        if (sg_read_oxfer(srp, buf, count - SZ_SG_HEADER)) {
+                                retval = -EFAULT;
+                                goto free_old_hdr;
+                        }
                 }
         } else
-                count = (old_hdr.result == 0) ? 0 : -EIO;
+                count = (old_hdr->result == 0) ? 0 : -EIO;
         sg_finish_rem_req(srp);
-        return count;
+        retval = count;
+free_old_hdr:
+        if (old_hdr)
+                kfree(old_hdr);
+        return retval;
 }
 
 static ssize_t
@@ -724,7 +763,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
         srp->data.sglist_len = 0;
         srp->data.bufflen = 0;
         srp->data.buffer = NULL;
-        hp->duration = jiffies; /* unit jiffies now, millisecs after done */
+        hp->duration = jiffies_to_msecs(jiffies);
 /* Now send everything of to mid-level. The next time we hear about this
    packet is when sg_cmd_done() is called (i.e. a callback). */
         scsi_do_req(SRpnt, (void *) cmnd,
@@ -937,8 +976,13 @@ sg_ioctl(struct inode *inode, struct file *filp,
                 if (!access_ok(VERIFY_WRITE, p, SZ_SG_REQ_INFO * SG_MAX_QUEUE))
                         return -EFAULT;
                 else {
-                        sg_req_info_t rinfo[SG_MAX_QUEUE];
-                        Sg_request *srp;
+                        sg_req_info_t *rinfo;
+                        unsigned int ms;
+
+                        rinfo = kmalloc(SZ_SG_REQ_INFO * SG_MAX_QUEUE,
+                                                                GFP_KERNEL);
+                        if (!rinfo)
+                                return -ENOMEM;
                         read_lock_irqsave(&sfp->rq_list_lock, iflags);
                         for (srp = sfp->headrp, val = 0; val < SG_MAX_QUEUE;
                              ++val, srp = srp ? srp->nextrp : srp) {
@@ -949,19 +993,30 @@ sg_ioctl(struct inode *inode, struct file *filp,
                                             srp->header.masked_status & 
                                             srp->header.host_status & 
                                             srp->header.driver_status;
-                                        rinfo[val].duration =
-                                            srp->done ? srp->header.duration :
-                                            jiffies_to_msecs(
-                                                jiffies - srp->header.duration);
+                                        if (srp->done)
+                                                rinfo[val].duration =
+                                                        srp->header.duration;
+                                        else {
+                                                ms = jiffies_to_msecs(jiffies);
+                                                rinfo[val].duration =
+                                                    (ms > srp->header.duration) ?
+                                                    (ms - srp->header.duration) : 0;
+                                        }
                                         rinfo[val].orphan = srp->orphan;
-                                        rinfo[val].sg_io_owned = srp->sg_io_owned;
-                                        rinfo[val].pack_id = srp->header.pack_id;
-                                        rinfo[val].usr_ptr = srp->header.usr_ptr;
+                                        rinfo[val].sg_io_owned =
+                                                        srp->sg_io_owned;
+                                        rinfo[val].pack_id =
+                                                        srp->header.pack_id;
+                                        rinfo[val].usr_ptr =
+                                                        srp->header.usr_ptr;
                                 }
                         }
                         read_unlock_irqrestore(&sfp->rq_list_lock, iflags);
-                        return (__copy_to_user(p, rinfo,
-                                SZ_SG_REQ_INFO * SG_MAX_QUEUE) ? -EFAULT : 0);
+                        result = __copy_to_user(p, rinfo, 
+                                                SZ_SG_REQ_INFO * SG_MAX_QUEUE);
+                        result = result ? -EFAULT : 0;
+                        kfree(rinfo);
+                        return result;
                 }
         case SG_EMULATED_HOST:
                 if (sdp->detached)
@@ -1208,11 +1263,12 @@ static int
 sg_mmap(struct file *filp, struct vm_area_struct *vma)
 {
         Sg_fd *sfp;
-        unsigned long req_sz = vma->vm_end - vma->vm_start;
+        unsigned long req_sz;
         Sg_scatter_hold *rsv_schp;
 
         if ((!filp) || (!vma) || (!(sfp = (Sg_fd *) filp->private_data)))
                 return -ENXIO;
+        req_sz = vma->vm_end - vma->vm_start;
         SCSI_LOG_TIMEOUT(3, printk("sg_mmap starting, vm_start=%p, len=%d\n",
                                    (void *) vma->vm_start, (int) req_sz));
         if (vma->vm_pgoff)
@@ -1259,6 +1315,7 @@ sg_cmd_done(Scsi_Cmnd * SCpnt)
         Sg_fd *sfp;
         Sg_request *srp = NULL;
         unsigned long iflags;
+        unsigned int ms;
 
         if (SCpnt && (SRpnt = SCpnt->sc_request))
                 srp = (Sg_request *) SRpnt->upper_private_data;
@@ -1295,9 +1352,9 @@ sg_cmd_done(Scsi_Cmnd * SCpnt)
         SCSI_LOG_TIMEOUT(4, printk("sg_cmd_done: %s, pack_id=%d, res=0x%x\n",
                 sdp->disk->disk_name, srp->header.pack_id, (int) SRpnt->sr_result));
         srp->header.resid = SCpnt->resid;
-        /* N.B. unit of duration changes here from jiffies to millisecs */
-        srp->header.duration =
-            jiffies_to_msecs(jiffies - srp->header.duration);
+        ms = jiffies_to_msecs(jiffies);
+        srp->header.duration = (ms > srp->header.duration) ?
+                                (ms - srp->header.duration) : 0;
         if (0 != SRpnt->sr_result) {
                 struct scsi_sense_hdr sshdr;
 
@@ -2395,7 +2452,7 @@ sg_add_request(Sg_fd * sfp)
         }
         if (resp) {
                 resp->nextrp = NULL;
-                resp->header.duration = jiffies;
+                resp->header.duration = jiffies_to_msecs(jiffies);
                 resp->my_cmdp = NULL;
         }
         write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
@@ -2990,6 +3047,7 @@ static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
         Sg_fd *fp;
         const sg_io_hdr_t *hp;
         const char * cp;
+        unsigned int ms;
 
         for (k = 0; (fp = sg_get_nth_sfp(sdp, k)); ++k) {
                 seq_printf(s, "   FD(%d): timeout=%dms bufflen=%d "
@@ -3028,10 +3086,13 @@ static void sg_proc_debug_helper(struct seq_file *s, Sg_device * sdp)
                                    srp->header.pack_id, blen);
                         if (srp->done)
                                 seq_printf(s, " dur=%d", hp->duration);
-                        else
+                        else {
+                                ms = jiffies_to_msecs(jiffies);
                                 seq_printf(s, " t_o/elap=%d/%d",
-                                  new_interface ? hp->timeout : jiffies_to_msecs(fp->timeout),
-                                  jiffies_to_msecs(hp->duration ? (jiffies - hp->duration) : 0));
+                                        (new_interface ? hp->timeout :
+                                                  jiffies_to_msecs(fp->timeout)),
+                                        (ms > hp->duration ? ms - hp->duration : 0));
+                        }
                         seq_printf(s, "ms sgat=%d op=0x%02x\n", usg,
                                    (int) srp->data.cmd_opcode);
                 }