[PATCH] idetape gcc 4.1 warning fix

In both the read and write cases it will return an error if
copy_{from/to}_user faults.  However, I let the driver try to read/write as
much as it can just as it normally would , then finally it returns an error
if there was one.  This was the most straight forward way to handle the
error , since there isn't a clear way to clean up the buffers on error .

I moved retval in idetape_chrdev_write() down into the actual code blocks
since it's really once used there, and it conflicted with my ret variable.

Fixes the following warning,

drivers/ide/ide-tape.c: In function ‘idetape_copy_stage_from_user’:
drivers/ide/ide-tape.c:2662: warning: ignoring return value of ‘copy_from_user’, declared with attribute warn_unused_result
drivers/ide/ide-tape.c: In function ‘idetape_copy_stage_to_user’:
drivers/ide/ide-tape.c:2689: warning: ignoring return value of ‘copy_to_user’, declared with attribute warn_unused_result

Signed-off-by: Daniel Walker <dwalker@mvista.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 33 insertions, 16 deletions

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index f04791a58df0..09f3a7dab28a 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -2646,21 +2646,23 @@ static idetape_stage_t *idetape_kmalloc_stage (idetape_tape_t *tape)
         return __idetape_kmalloc_stage(tape, 0, 0);
 }
 
-static void idetape_copy_stage_from_user (idetape_tape_t *tape, idetape_stage_t *stage, const char __user *buf, int n)
+static int idetape_copy_stage_from_user (idetape_tape_t *tape, idetape_stage_t *stage, const char __user *buf, int n)
 {
         struct idetape_bh *bh = tape->bh;
         int count;
+        int ret = 0;
 
         while (n) {
 #if IDETAPE_DEBUG_BUGS
                 if (bh == NULL) {
                         printk(KERN_ERR "ide-tape: bh == NULL in "
                                 "idetape_copy_stage_from_user\n");
-                        return;
+                        return 1;
                 }
 #endif /* IDETAPE_DEBUG_BUGS */
                 count = min((unsigned int)(bh->b_size - atomic_read(&bh->b_count)), (unsigned int)n);
-                copy_from_user(bh->b_data + atomic_read(&bh->b_count), buf, count);
+                if (copy_from_user(bh->b_data + atomic_read(&bh->b_count), buf, count))
+                        ret = 1;
                 n -= count;
                 atomic_add(count, &bh->b_count);
                 buf += count;
@@ -2671,23 +2673,26 @@ static void idetape_copy_stage_from_user (idetape_tape_t *tape, idetape_stage_t
                 }
         }
         tape->bh = bh;
+        return ret;
 }
 
-static void idetape_copy_stage_to_user (idetape_tape_t *tape, char __user *buf, idetape_stage_t *stage, int n)
+static int idetape_copy_stage_to_user (idetape_tape_t *tape, char __user *buf, idetape_stage_t *stage, int n)
 {
         struct idetape_bh *bh = tape->bh;
         int count;
+        int ret = 0;
 
         while (n) {
 #if IDETAPE_DEBUG_BUGS
                 if (bh == NULL) {
                         printk(KERN_ERR "ide-tape: bh == NULL in "
                                 "idetape_copy_stage_to_user\n");
-                        return;
+                        return 1;
                 }
 #endif /* IDETAPE_DEBUG_BUGS */
                 count = min(tape->b_count, n);
-                copy_to_user(buf, tape->b_data, count);
+                if  (copy_to_user(buf, tape->b_data, count))
+                        ret = 1;
                 n -= count;
                 tape->b_data += count;
                 tape->b_count -= count;
@@ -2700,6 +2705,7 @@ static void idetape_copy_stage_to_user (idetape_tape_t *tape, char __user *buf,
                         }
                 }
         }
+        return ret;
 }
 
 static void idetape_init_merge_stage (idetape_tape_t *tape)
@@ -3719,6 +3725,7 @@ static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
         struct ide_tape_obj *tape = ide_tape_f(file);
         ide_drive_t *drive = tape->drive;
         ssize_t bytes_read,temp, actually_read = 0, rc;
+        ssize_t ret = 0;
 
 #if IDETAPE_DEBUG_LOG
         if (tape->debug_level >= 3)
@@ -3737,7 +3744,8 @@ static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
                 return (0);
         if (tape->merge_stage_size) {
                 actually_read = min((unsigned int)(tape->merge_stage_size), (unsigned int)count);
-                idetape_copy_stage_to_user(tape, buf, tape->merge_stage, actually_read);
+                if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, actually_read))
+                        ret = -EFAULT;
                 buf += actually_read;
                 tape->merge_stage_size -= actually_read;
                 count -= actually_read;
@@ -3746,7 +3754,8 @@ static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
                 bytes_read = idetape_add_chrdev_read_request(drive, tape->capabilities.ctl);
                 if (bytes_read <= 0)
                         goto finish;
-                idetape_copy_stage_to_user(tape, buf, tape->merge_stage, bytes_read);
+                if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, bytes_read))
+                        ret = -EFAULT;
                 buf += bytes_read;
                 count -= bytes_read;
                 actually_read += bytes_read;
@@ -3756,7 +3765,8 @@ static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
                 if (bytes_read <= 0)
                         goto finish;
                 temp = min((unsigned long)count, (unsigned long)bytes_read);
-                idetape_copy_stage_to_user(tape, buf, tape->merge_stage, temp);
+                if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, temp))
+                        ret = -EFAULT;
                 actually_read += temp;
                 tape->merge_stage_size = bytes_read-temp;
         }
@@ -3769,7 +3779,8 @@ finish:
                 idetape_space_over_filemarks(drive, MTFSF, 1);
                 return 0;
         }
-        return actually_read;
+
+        return (ret) ? ret : actually_read;
 }
 
 static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
@@ -3777,7 +3788,8 @@ static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
 {
         struct ide_tape_obj *tape = ide_tape_f(file);
         ide_drive_t *drive = tape->drive;
-        ssize_t retval, actually_written = 0;
+        ssize_t actually_written = 0;
+        ssize_t ret = 0;
 
         /* The drive is write protected. */
         if (tape->write_prot)
@@ -3813,7 +3825,7 @@ static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
                  *      some drives (Seagate STT3401A) will return an error.
                  */
                 if (drive->dsc_overlap) {
-                        retval = idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, 0, tape->merge_stage->bh);
+                        ssize_t retval = idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, 0, tape->merge_stage->bh);
                         if (retval < 0) {
                                 __idetape_kfree_stage(tape->merge_stage);
                                 tape->merge_stage = NULL;
@@ -3834,12 +3846,14 @@ static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
                 }
 #endif /* IDETAPE_DEBUG_BUGS */
                 actually_written = min((unsigned int)(tape->stage_size - tape->merge_stage_size), (unsigned int)count);
-                idetape_copy_stage_from_user(tape, tape->merge_stage, buf, actually_written);
+                if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, actually_written))
+                                ret = -EFAULT;
                 buf += actually_written;
                 tape->merge_stage_size += actually_written;
                 count -= actually_written;
 
                 if (tape->merge_stage_size == tape->stage_size) {
+                        ssize_t retval;
                         tape->merge_stage_size = 0;
                         retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
                         if (retval <= 0)
@@ -3847,7 +3861,9 @@ static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
                 }
         }
         while (count >= tape->stage_size) {
-                idetape_copy_stage_from_user(tape, tape->merge_stage, buf, tape->stage_size);
+                ssize_t retval;
+                if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, tape->stage_size))
+                        ret = -EFAULT;
                 buf += tape->stage_size;
                 count -= tape->stage_size;
                 retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
@@ -3857,10 +3873,11 @@ static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
         }
         if (count) {
                 actually_written += count;
-                idetape_copy_stage_from_user(tape, tape->merge_stage, buf, count);
+                if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, count))
+                        ret = -EFAULT;
                 tape->merge_stage_size += count;
         }
-        return (actually_written);
+        return (ret) ? ret : actually_written;
 }
 
 static int idetape_write_filemark (ide_drive_t *drive)