From 0de2dfc95b476830d1628c20c45eb6762b2c1cb8 Mon Sep 17 00:00:00 2001
From: Giacomo Tesio <giacomo@tesio.it>
Date: Thu, 12 Jan 2017 00:35:27 +0100
Subject: [PATCH] kernel: fix /dev/swap and `stats -m`

---
 sys/src/cmd/stats.c            |  2 +-
 sys/src/kern/port/devcons.c    | 33 +++++++++++++--------------------
 sys/src/kern/port/umem/pages.c | 19 +++++++++++--------
 sys/src/kern/port/umem/umem.h  | 12 ++++++++++--
 4 files changed, 35 insertions(+), 31 deletions(-)

diff --git a/sys/src/cmd/stats.c b/sys/src/cmd/stats.c
index e725218..1fc58d5 100644
--- a/sys/src/cmd/stats.c
+++ b/sys/src/cmd/stats.c
@@ -467,7 +467,7 @@ readswap(Machine *m, uint64_t *a)
 {
 	if(strstr(m->buf, "memory\n")){
 		/* new /dev/swap - skip first 3 numbers */
-		if(!readnums(m, 7, a, 1))
+		if(!readnums(m, 5, a, 1))
 			return 0;
 		a[0] = a[3];
 		a[1] = a[4];
diff --git a/sys/src/kern/port/devcons.c b/sys/src/kern/port/devcons.c
index 47b61a3..0218fe4 100644
--- a/sys/src/kern/port/devcons.c
+++ b/sys/src/kern/port/devcons.c
@@ -831,7 +831,8 @@ consread(Chan *c, void *buf, long n, int64_t off)
 {
 	uint64_t l;
 	Mach *mp;
-	char *b, *bp, *s, ch;
+	MemoryStats mstats;
+	char *b, *bp, ch;
 	char tmp[6*NUMSIZE+1];		/* must be >= 6*NUMSIZE (Qcputime) */
 	int i, id, send;
 	long offset;
@@ -997,26 +998,18 @@ consread(Chan *c, void *buf, long n, int64_t off)
 		return n;
 
 	case Qswap:
-		bp = smalloc(READSTR);
-		if(waserror()){
-			free(bp);
-			nexterror();
-		}
-		s = pages_stats(bp, bp+READSTR);
-		s = seprintphysstats(s, bp+READSTR);
-		l = s - bp;
-		b = buf;
-		i = readstr(offset, b, n, bp);
-		poperror();
-		free(bp);
-		b += i;
-		n -= i;
-		if(offset > l)
-			offset -= l;
-		else
-			offset = 0;
+		memory_stats(&mstats);
+		snprint(tmp, sizeof tmp,
+			"%llud memory\n"
+			"%llud pagesize\n"
+			"%lud kernel\n"
+			"%lud/%lud user\n",
+			mstats.memory,
+			(unsigned long)PGSZ,
+			mstats.kernel,
+			mstats.user, mstats.user_available);
 
-		return i + mallocreadsummary(c, b, n, offset);
+		return readstr(offset, buf, n, tmp);
 
 	case Qsysname:
 		if(sysname == nil)
diff --git a/sys/src/kern/port/umem/pages.c b/sys/src/kern/port/umem/pages.c
index 25b5f85..8ffb3ac 100644
--- a/sys/src/kern/port/umem/pages.c
+++ b/sys/src/kern/port/umem/pages.c
@@ -100,15 +100,18 @@ umem_init(void)
 
 }
 
-char*
-pages_stats(char *s, char *e)
+void
+memory_stats(MemoryStats *stats)
 {
-	plock();
-	s = seprint(s, e, "%lud/%lud %dK user pages avail\n",
-		pool.freepages + pool.blankpages,
-		pool.npages, (pool.freepages + pool.blankpages)*PGSZ/KiB);
-	punlock();
-	return s;
+	uintptr_t km;
+	if(stats == nil)
+		panic("memory_stats: nil pointer, pc %#p", getcallerpc());
+	km = ROUNDUP((uintptr_t)end - KTZERO, PGSZ);
+	km += ROUNDDN(sys->vmunmapped - (uintptr_t)end, PGSZ);
+	stats->memory = sys->pmoccupied;
+	stats->kernel = km;
+	stats->user_available = pool.npages*PGSZ;
+	stats->user = (pool.npages - pool.blankpages - pool.freepages)*PGSZ;
 }
 
 KMap*
diff --git a/sys/src/kern/port/umem/umem.h b/sys/src/kern/port/umem/umem.h
index 29702a5..23f345d 100644
--- a/sys/src/kern/port/umem/umem.h
+++ b/sys/src/kern/port/umem/umem.h
@@ -55,8 +55,6 @@ extern int page_dispose(PagePointer *slot);
  */
 extern int page_assign(PagePointer *target, PagePointer page);
 
-extern char* pages_stats(char *s, char *e);
-
 /* Replace the page in *slot with a copy
  *
  * Returns 1 on success, 0 on failure.
@@ -247,3 +245,13 @@ extern void proc_check_pages(void);
 extern int proc_own_pagepool(Proc *p);
 extern int proc_segment_detach(Proc *p, uintptr_t va);
 
+typedef struct MemoryStats
+{
+	unsigned long memory;
+	unsigned long kernel;
+	unsigned long user_available;
+	unsigned long user;
+} MemoryStats;
+
+/* fills stats with memory statistics */
+extern void memory_stats(MemoryStats *stats);