[Patch] shmmin behaviour back to 2.2 behaviour

From: Christoph Rohland <cr@sap.com>
To: Linus Torvalds <torvalds@transmeta.com>
Cc: linux-kernel@vger.kernel.org, Dave Gilbert <gilbertd@treblig.org>
Subject: [Patch] shmmin behaviour back to 2.2 behaviour
Date: 27 Dec 2000 11:32:41 +0100	[thread overview]
Message-ID: <m3d7eeb1pa.fsf@linux.local> (raw)

Hi Linus,

The following patchlet bring the handling of shmget with size zero
back to the 2.2 behaviour. There seem to be programs out, which
(erroneously) rely on this.

Greetings
                Christoph

diff -uNr c/include/linux/shm.h c1/include/linux/shm.h

--- c/include/linux/shm.h	Fri Dec 22 10:20:08 2000
+++ c1/include/linux/shm.h	Tue Dec 26 19:52:15 2000
@@ -10,7 +10,7 @@
  */
 
 #define SHMMAX 0x2000000		 /* max shared seg size (bytes) */
-#define SHMMIN 0			 /* min shared seg size (bytes) */
+#define SHMMIN 1			 /* min shared seg size (bytes) */
 #define SHMMNI 4096			 /* max num of segs system wide */
 #define SHMALL (SHMMAX/PAGE_SIZE*(SHMMNI/16)) /* max shm system wide (pages) */
 #define SHMSEG SHMMNI			 /* max shared segs per process */
diff -uNr c/ipc/shm.c c1/ipc/shm.c
--- c/ipc/shm.c	Fri Dec 22 10:05:38 2000
+++ c1/ipc/shm.c	Tue Dec 26 19:53:35 2000
@@ -179,6 +179,9 @@
 	char name[13];
 	int id;
 
+	if (size < SHMMIN || size > shm_ctlmax)
+		return -EINVAL;
+
 	if (shm_tot + numpages >= shm_ctlall)
 		return -ENOSPC;
 
@@ -222,9 +225,6 @@
 {
 	struct shmid_kernel *shp;
 	int err, id = 0;
-
-	if (size < SHMMIN || size > shm_ctlmax)
-		return -EINVAL;
 
 	down(&shm_ids.sem);
 	if (key == IPC_PRIVATE) {

-
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