Module refcounting in fs/proc/inode.c

Module refcounting in fs/proc/inode.c

[Doug Ledford]

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This patch should make module ref counting safe in the proc filesystem.  
Without it, accessing /proc/scsi/aic7xxx/0 renders the aic7xxx module 
unloadable.  However, I assume that we can call put_de() on the de we have 
at the time that the module ref inc attempt might fail.  If that's not 
right, then someone who knows de ops will have to correct this patch.



-- 
  Doug Ledford <dledford@redhat.com>     919-754-3700 x44233
         Red Hat, Inc. 
         1801 Varsity Dr.
         Raleigh, NC 27606
  

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===== fs/proc/inode.c 1.17 vs edited =====
--- 1.17/fs/proc/inode.c	Sat Sep 28 11:36:29 2002
+++ edited/fs/proc/inode.c	Sun Nov 17 18:22:38 2002
@@ -73,7 +73,7 @@
 	de = PROC_I(inode)->pde;
 	if (de) {
 		if (de->owner)
-			__MOD_DEC_USE_COUNT(de->owner);
+			module_put(de->owner);
 		de_put(de);
 	}
 }
@@ -201,7 +201,8 @@
 		if (de->nlink)
 			inode->i_nlink = de->nlink;
 		if (de->owner)
-			__MOD_INC_USE_COUNT(de->owner);
+			if(!try_module_get(de->owner))
+				goto out_fail;
 		if (de->proc_iops)
 			inode->i_op = de->proc_iops;
 		if (de->proc_fops)