Messages in this thread Patch in this message | | | Date | Mon, 7 Aug 2006 18:00:44 -0500 | Subject | Re: [PATCH] Chardev checking of overlapping ranges is incorrect. | From | (Linas Vepstas) |
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On Mon, Aug 07, 2006 at 05:55:55PM -0500, linas wrote: > > The current code in register_chrdev_region() attempts to check
A debug printk escaped with that patch. Here's the proper patch. --linas
[PATCH] Chardev checking of overlapping ranges is incorrect.
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 <linas@austin.ibm.com>
---- fs/char_dev.c | 8 ++++++-- 1 file changed, 6 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 17:57:51.000000000 -0500 @@ -113,9 +113,13 @@ __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; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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