The current code in register_chrdev_region() attempts to check
for overlapping regions of minor device numbers, but performs
that check incorrectly. For example, if a device with minor
numbers 128, 129, 130 is registered first, and a device with
minor number 3,4,5 is registered later, then the later range
is incorrectly identified as "overlapping" (since 130>3),
when clearly this is the wrong conclusion.
This patch fixes the overlap check to work correctly.
Signed-off-by: Signed-off-by: Linas Vepstas <[email protected]>
----
fs/char_dev.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
Index: linux-2.6.18-rc3-mm2/fs/char_dev.c
===================================================================
--- linux-2.6.18-rc3-mm2.orig/fs/char_dev.c 2006-08-07 17:16:53.000000000 -0500
+++ linux-2.6.18-rc3-mm2/fs/char_dev.c 2006-08-07 17:18:59.000000000 -0500
@@ -93,6 +93,7 @@ __register_chrdev_region(unsigned int ma
}
if (i == 0) {
+printk ("duude egister_chrdev_regio no major !!\n");
ret = -EBUSY;
goto out;
}
@@ -113,9 +114,13 @@ __register_chrdev_region(unsigned int ma
(((*cp)->baseminor >= baseminor) ||
((*cp)->baseminor + (*cp)->minorct > baseminor))))
break;
+
+ /* Check for overlap of minor ranges */
if (*cp && (*cp)->major == major &&
- (((*cp)->baseminor < baseminor + minorct) ||
- ((*cp)->baseminor + (*cp)->minorct > baseminor))) {
+ ((((*cp)->baseminor <= baseminor) &&
+ ((*cp)->baseminor + (*cp)->minorct >= baseminor)) ||
+ (((*cp)->baseminor >= baseminor) &&
+ ((*cp)->baseminor <= baseminor+minorct)))) {
ret = -EBUSY;
goto out;
}
-
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