SysV IPC, kernel 2.4.3

PATCH New Scott Maxwell 1 participant 1 message Apr 5, 2001

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Scott Maxwell

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2001-04-05 05:41 UTC #0 lore raw

PATCH 1/1 SysV IPC, kernel 2.4.3

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.

Signature · 4 lines

-------------------------+--------------------------------------------
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

ipc/msg.c +5 ~~-12~~

diff -urN linux-2.4.3/ipc/msg.c linux/ipc/msg.c
@@ -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;
 			}
 		}

ipc/sem.c +2 -2

diff -urN linux-2.4.3/ipc/sem.c linux/ipc/sem.c
@@ -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;
 		}

ipc/util.c +2 -1

diff -urN linux-2.4.3/ipc/util.c linux/ipc/util.c
@@ -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;
 }