TODO: drivers/pcmcia/ds.c: ds_read & ds_write. SMP locks are missing fix

[Yong Chi]

Hopefully this will do for SMP locks.  =)

Todo list also said that on UP, sleep_on() use is unsafe.  It uses
"interruptible_sleep_on()" and "wake_up_interruptible()" calls. Are they
not safe on UP?

Thanks



--- ds.c.bak    Wed Oct 11 13:05:16 2000
+++ ds.c        Thu Oct 12 11:25:20 2000
@@ -95,6 +95,7 @@
     u_int              user_magic;
     int                        event_head, event_tail;
     event_t            event[MAX_EVENTS];
+    spinlock_t          lock;
     struct user_info_t *next;
 } user_info_t;
 
@@ -567,6 +568,7 @@
     user->event_tail = user->event_head = 0;
     user->next = s->user;
     user->user_magic = USER_MAGIC;
+    spin_lock_init(&user->lock);
     s->user = user;
     file->private_data = user;
     
@@ -616,6 +618,7 @@
     socket_t i = MINOR(file->f_dentry->d_inode->i_rdev);
     socket_info_t *s;
     user_info_t *user;
+    ssize_t retval=4;
 
     DEBUG(2, "ds_read(socket %d)\n", i);
     
@@ -625,16 +628,23 @@
        return -EINVAL;
     s = &socket_table[i];
     user = file->private_data;
-    if (CHECK_USER(user))
-       return -EIO;
-    
+    spin_lock(&user->lock);
+    if (CHECK_USER(user)) {
+       retval= -EIO;
+        goto read_out;
+    }
+
     if (queue_empty(user)) {
        interruptible_sleep_on(&s->queue);
        if (signal_pending(current))
-           return -EINTR;
+           retval= -EINTR;
+            goto read_out;
     }
     put_user(get_queued_event(user), (int *)buf);
-    return 4;
+
+read_out:
+    spin_unlock(&user->lock);
+    return retval;
 } /* ds_read */
 
 /*====================================================================*/
@@ -645,6 +655,7 @@
     socket_t i = MINOR(file->f_dentry->d_inode->i_rdev);
     socket_info_t *s;
     user_info_t *user;
+    ssize_t retval=4;
 
     DEBUG(2, "ds_write(socket %d)\n", i);
     
@@ -656,18 +667,25 @@
        return -EBADF;
     s = &socket_table[i];
     user = file->private_data;
-    if (CHECK_USER(user))
-       return -EIO;
+    spin_lock(&user->lock);
+    if (CHECK_USER(user)) {
+       retval= -EIO;
+       goto write_out;
+    }
 
     if (s->req_pending) {
        s->req_pending--;
        get_user(s->req_result, (int *)buf);
        if ((s->req_result != 0) || (s->req_pending == 0))
            wake_up_interruptible(&s->request);
-    } else
-       return -EIO;
+    } else {
+       retval= -EIO;
+       goto write_out;
+    }
 
-    return 4;
+write_out:
+    spin_unlock(&user->lock);
+    return retval;
 } /* ds_write */
 
 /*====================================================================*/