[PATCH] SysV IPC, kernel 2.4.3

[PATCH] SysV IPC, kernel 2.4.3

[Scott Maxwell]

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This patch contains several small bug fixes and micro-optimizations
for SysV IPC code in the 2.4.3 kernel.  Summary:

	* testmsg(): "return expr;" beats "if (expr) return 1; ... return 0;"
	* pipelined_send() was setting q_lspid instead of q_lrpid.
	* sys_msgrcv() had redundant found_msg assignments.
	* freeundos() had unused parameter (sma).
	* ipc_alloc(): Kernel oops if initial allocation failed.

I'm having unrelated problems getting 2.4.3 to work with my test
hardware, so I have tested these changes under 2.4.1 only.  They work
fine for me under 2.4.1, though.  Please email me if you see any
problems or if Netscape mail mangles this post (I haven't tried this
before).  Thanks.

-- 
-------------------------+--------------------------------------------
R H L U  Scott Maxwell:  | ``Life results from the non-random survival
E A I X     maxwell@     |   of randomly varying replicators.''
D T N 6 ScottMaxwell.org |     -- Richard Dawkins

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diff -urN linux-2.4.3/ipc/msg.c linux/ipc/msg.c
--- linux-2.4.3/ipc/msg.c	Mon Feb 19 10:18:18 2001
+++ linux/ipc/msg.c	Wed Apr  4 00:38:21 2001
@@ -582,17 +582,11 @@
 		case SEARCH_ANY:
 			return 1;
 		case SEARCH_LESSEQUAL:
-			if(msg->m_type <=type)
-				return 1;
-			break;
+			return msg->m_type <=type;
 		case SEARCH_EQUAL:
-			if(msg->m_type == type)
-				return 1;
-			break;
+			return msg->m_type == type;
 		case SEARCH_NOTEQUAL:
-			if(msg->m_type != type)
-				return 1;
-			break;
+			return msg->m_type != type;
 	}
 	return 0;
 }
@@ -613,7 +607,8 @@
 				wake_up_process(msr->r_tsk);
 			} else {
 				msr->r_msg = msg;
-				msq->q_lspid = msr->r_tsk->pid;
+				/* Was q_lspid; surely, this was the intent. */
+				msq->q_lrpid = msr->r_tsk->pid;
 				msq->q_rtime = CURRENT_TIME;
 				wake_up_process(msr->r_tsk);
 				return 1;
@@ -753,10 +748,8 @@
 		if(testmsg(msg,msgtyp,mode)) {
 			found_msg = msg;
 			if(mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
-				found_msg=msg;
 				msgtyp=msg->m_type-1;
 			} else {
-				found_msg=msg;
 				break;
 			}
 		}
diff -urN linux-2.4.3/ipc/sem.c linux/ipc/sem.c
--- linux-2.4.3/ipc/sem.c	Mon Feb 19 10:18:18 2001
+++ linux/ipc/sem.c	Mon Apr  2 20:51:37 2001
@@ -775,7 +775,7 @@
 	}
 }
 
-static struct sem_undo* freeundos(struct sem_array *sma, struct sem_undo* un)
+static struct sem_undo* freeundos(struct sem_undo* un)
 {
 	struct sem_undo* u;
 	struct sem_undo** up;
@@ -878,7 +878,7 @@
 			if(un->semid==semid)
 				break;
 			if(un->semid==-1)
-				un=freeundos(sma,un);
+				un=freeundos(un);
 			 else
 				un=un->proc_next;
 		}
diff -urN linux-2.4.3/ipc/util.c linux/ipc/util.c
--- linux-2.4.3/ipc/util.c	Mon Feb 19 10:18:18 2001
+++ linux/ipc/util.c	Mon Apr  2 20:39:55 2001
@@ -75,7 +75,8 @@
 		ids->size = 0;
 	}
 	ids->ary = SPIN_LOCK_UNLOCKED;
-	for(i=0;i<size;i++)
+	/* Was looping i=[0..size], causing kernel panic if alloc failed. */
+	for(i=0;i<ids->size;i++)
 		ids->entries[i].p = NULL;
 }