kernel: fix tprof on multiprocessor

segclock() has to be called from hzclock(), otherwise
only processes running on cpu0 would catche the interrupt
and the time delta would be wrong.

lock the segment when allocating Seg->profile as
profile ctl might be issued from multiple processes.
Proc->debug qlock is not sufficient.

Seg->profile can never be freed or reallocated once
set as the timer interrupt accesses it without any
locking.

1 files changed, 15 insertions, 26 deletions

diff --git a/sys/src/9/port/devproc.c b/sys/src/9/port/devproc.c
index d54fcb507..bb6d3d970 100644
--- a/sys/src/9/port/devproc.c
+++ b/sys/src/9/port/devproc.c
@@ -1,6 +1,5 @@
 #include	"u.h"
 #include	<trace.h>
-#include	"tos.h"
 #include	"../port/lib.h"
 #include	"mem.h"
 #include	"dat.h"
@@ -167,22 +166,6 @@ static int topens;
 static int tproduced, tconsumed;
 void (*proctrace)(Proc*, int, vlong);
 
-static void
-profclock(Ureg *ur, Timer *)
-{
-	Tos *tos;
-
-	if(up == nil || up->state != Running)
-		return;
-
-	/* user profiling clock */
-	if(userureg(ur)){
-		tos = (Tos*)(USTKTOP-sizeof(Tos));
-		tos->clock += TK2MS(1);
-		segclock(ur->pc);
-	}
-}
-
 static int lenwatchpt(Proc *);
 
 static int
@@ -304,7 +287,6 @@ procinit(void)
 {
 	if(conf.nproc >= (1<<(16-QSHIFT))-1)
 		print("warning: too many procs for devproc\n");
-	addclock0link((void (*)(void))profclock, 113);	/* Relative prime to HZ */
 }
 
 static Chan*
@@ -1454,7 +1436,8 @@ void
 procctlreq(Proc *p, char *va, int n)
 {
 	Segment *s;
-	int npc, pri;
+	uintptr npc;
+	int pri;
 	Cmdbuf *cb;
 	Cmdtab *ct;
 	vlong time;
@@ -1520,14 +1503,20 @@ procctlreq(Proc *p, char *va, int n)
 		break;
 	case CMprofile:
 		s = p->seg[TSEG];
-		if(s == nil || (s->type&SG_TYPE) != SG_TEXT)
-			error(Ebadctl);
-		if(s->profile != nil)
-			free(s->profile);
+		if(s == nil || (s->type&SG_TYPE) != SG_TEXT)	/* won't expand */
+			error(Egreg);
+		eqlock(s);
 		npc = (s->top-s->base)>>LRESPROF;
-		s->profile = malloc(npc*sizeof(*s->profile));
-		if(s->profile == nil)
-			error(Enomem);
+		if(s->profile == nil){
+			s->profile = malloc(npc*sizeof(*s->profile));
+			if(s->profile == nil){
+				qunlock(s);
+				error(Enomem);
+			}
+		} else {
+			memset(s->profile, 0, npc*sizeof(*s->profile));
+		}
+		qunlock(s);
 		break;
 	case CMstart:
 		if(p->state != Stopped)