[linux-usb-devel] [PATCH] driver/usb/scanner.c

[Frank Zago]

Hi,

This patch does:

- remove the semaphore from interrupt handler (semaphore are not allowed
  under ints). And no locking is necessary currently.

- fixes a problem with MOD_INC_USE_COUNT / MOD_DEC_USE_COUNT in
  open_scanner()

- fixes a race in probe_scanner()

- adds two missing "up(&scn_mutex)" in probe_scanner().

The patch has been tested.

Please consider and apply.

Regards,
  Frank.

--- scanner.c.org       Wed Nov 21 22:49:47 2001
+++ scanner.c   Thu Nov 22 00:29:55 2001
@@ -324,17 +324,16 @@
        struct scn_usb_data *scn;
        unsigned char *data;
        scn = urb->context;
-       down(&(scn->sem));
+
        data = &scn->button;
        data += 0;              /* Keep gcc from complaining about unused var */
 
        if (urb->status) {
-               up(&(scn->sem));
                return;
        }
 
        dbg("irq_scanner(%d): data:%x", scn->scn_minor, *data);
-       up(&(scn->sem));
+
        return;
 }
 
@@ -357,9 +356,9 @@
        dbg("open_scanner: scn_minor:%d", scn_minor);
 
        if (!p_scn_table[scn_minor]) {
-               up(&scn_mutex);
                err("open_scanner(%d): Unable to access minor data", scn_minor);
-               return -ENODEV;
+               err = -ENODEV;
+               goto out_error;
        }
 
        scn = p_scn_table[scn_minor];
@@ -939,6 +938,7 @@
 /* Check to make sure that the last slot isn't already taken */
        if (p_scn_table[scn_minor]) {
                err("probe_scanner: No more minor devices remaining.");
+               up(&scn_mutex);
                return NULL;
        }
 
@@ -946,6 +946,7 @@
 
        if (!(scn = kmalloc (sizeof (struct scn_usb_data), GFP_KERNEL))) {
                err("probe_scanner: Out of memory.");
+               up(&scn_mutex);
                return NULL;
        }
        memset (scn, 0, sizeof(struct scn_usb_data));
@@ -1028,9 +1029,11 @@
        if (scn->devfs == NULL)
                dbg("scanner%d: device node registration failed", scn_minor);
 
+       p_scn_table[scn_minor] = scn;
+
        up(&scn_mutex);
 
-       return p_scn_table[scn_minor] = scn;
+       return scn;
 }
 
 static void