Add a drain function for struct sysctl_req, and use it for a variety of

handlers, some of which had to do awkward things to get a large enough
FIXEDLEN buffer.

Note that some sysctl handlers were explicitly outputting a trailing NUL
byte.  This behaviour was preserved, though it should not be necessary.

Reviewed by:	phk

3 files changed, 17 insertions, 73 deletions

diff --git a/sys/vm/uma_core.c b/sys/vm/uma_core.c
index 558b4c7..23b88ee 100644
--- a/sys/vm/uma_core.c
+++ b/sys/vm/uma_core.c
@@ -3175,36 +3175,16 @@ sysctl_vm_zone_stats(SYSCTL_HANDLER_ARGS)
 	uma_keg_t kz;
 	uma_zone_t z;
 	uma_keg_t k;
-	char *buffer;
-	int buflen, count, error, i;
+	int count, error, i;
 
-	mtx_lock(&uma_mtx);
-restart:
-	mtx_assert(&uma_mtx, MA_OWNED);
-	count = 0;
-	LIST_FOREACH(kz, &uma_kegs, uk_link) {
-		LIST_FOREACH(z, &kz->uk_zones, uz_link)
-			count++;
-	}
-	mtx_unlock(&uma_mtx);
-
-	buflen = sizeof(ush) + count * (sizeof(uth) + sizeof(ups) *
-	    (mp_maxid + 1)) + 1;
-	buffer = malloc(buflen, M_TEMP, M_WAITOK | M_ZERO);
+	sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
 
+	count = 0;
 	mtx_lock(&uma_mtx);
-	i = 0;
 	LIST_FOREACH(kz, &uma_kegs, uk_link) {
 		LIST_FOREACH(z, &kz->uk_zones, uz_link)
-			i++;
-	}
-	if (i > count) {
-		free(buffer, M_TEMP);
-		goto restart;
+			count++;
 	}
-	count =  i;
-
-	sbuf_new(&sbuf, buffer, buflen, SBUF_FIXEDLEN);
 
 	/*
 	 * Insert stream header.
@@ -3213,11 +3193,7 @@ restart:
 	ush.ush_version = UMA_STREAM_VERSION;
 	ush.ush_maxcpus = (mp_maxid + 1);
 	ush.ush_count = count;
-	if (sbuf_bcat(&sbuf, &ush, sizeof(ush)) < 0) {
-		mtx_unlock(&uma_mtx);
-		error = ENOMEM;
-		goto out;
-	}
+	(void)sbuf_bcat(&sbuf, &ush, sizeof(ush));
 
 	LIST_FOREACH(kz, &uma_kegs, uk_link) {
 		LIST_FOREACH(z, &kz->uk_zones, uz_link) {
@@ -3250,12 +3226,7 @@ restart:
 			uth.uth_frees = z->uz_frees;
 			uth.uth_fails = z->uz_fails;
 			uth.uth_sleeps = z->uz_sleeps;
-			if (sbuf_bcat(&sbuf, &uth, sizeof(uth)) < 0) {
-				ZONE_UNLOCK(z);
-				mtx_unlock(&uma_mtx);
-				error = ENOMEM;
-				goto out;
-			}
+			(void)sbuf_bcat(&sbuf, &uth, sizeof(uth));
 			/*
 			 * While it is not normally safe to access the cache
 			 * bucket pointers while not on the CPU that owns the
@@ -3280,21 +3251,14 @@ restart:
 				ups.ups_allocs = cache->uc_allocs;
 				ups.ups_frees = cache->uc_frees;
 skip:
-				if (sbuf_bcat(&sbuf, &ups, sizeof(ups)) < 0) {
-					ZONE_UNLOCK(z);
-					mtx_unlock(&uma_mtx);
-					error = ENOMEM;
-					goto out;
-				}
+				(void)sbuf_bcat(&sbuf, &ups, sizeof(ups));
 			}
 			ZONE_UNLOCK(z);
 		}
 	}
 	mtx_unlock(&uma_mtx);
-	sbuf_finish(&sbuf);
-	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
-out:
-	free(buffer, M_TEMP);
+	error = sbuf_finish(&sbuf);
+	sbuf_delete(&sbuf);
 	return (error);
 }
 
diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
index e75c340..26e4981 100644
--- a/sys/vm/vm_phys.c
+++ b/sys/vm/vm_phys.c
@@ -123,12 +123,9 @@ sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS)
 {
 	struct sbuf sbuf;
 	struct vm_freelist *fl;
-	char *cbuf;
-	const int cbufsize = vm_nfreelists*(VM_NFREEORDER + 1)*81;
 	int error, flind, oind, pind;
 
-	cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
-	sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
+	sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
 	for (flind = 0; flind < vm_nfreelists; flind++) {
 		sbuf_printf(&sbuf, "\nFREE LIST %d:\n"
 		    "\n  ORDER (SIZE)  |  NUMBER"
@@ -149,10 +146,8 @@ sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS)
 			sbuf_printf(&sbuf, "\n");
 		}
 	}
-	sbuf_finish(&sbuf);
-	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
+	error = sbuf_finish(&sbuf);
 	sbuf_delete(&sbuf);
-	free(cbuf, M_TEMP);
 	return (error);
 }
 
@@ -164,12 +159,9 @@ sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS)
 {
 	struct sbuf sbuf;
 	struct vm_phys_seg *seg;
-	char *cbuf;
-	const int cbufsize = VM_PHYSSEG_MAX*(VM_NFREEORDER + 1)*81;
 	int error, segind;
 
-	cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
-	sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
+	sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
 	for (segind = 0; segind < vm_phys_nsegs; segind++) {
 		sbuf_printf(&sbuf, "\nSEGMENT %d:\n\n", segind);
 		seg = &vm_phys_segs[segind];
@@ -180,10 +172,8 @@ sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS)
 		sbuf_printf(&sbuf, "domain:    %d\n", seg->domain);
 		sbuf_printf(&sbuf, "free list: %p\n", seg->free_queues);
 	}
-	sbuf_finish(&sbuf);
-	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
+	error = sbuf_finish(&sbuf);
 	sbuf_delete(&sbuf);
-	free(cbuf, M_TEMP);
 	return (error);
 }
 
@@ -195,23 +185,18 @@ static int
 sysctl_vm_phys_lookup_lists(SYSCTL_HANDLER_ARGS)
 {
 	struct sbuf sbuf;
-	char *cbuf;
-	const int cbufsize = (vm_nfreelists + 1) * VM_NDOMAIN * 81;
 	int domain, error, flind, ndomains;
 
 	ndomains = vm_nfreelists - VM_NFREELIST + 1;
-	cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
-	sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
+	sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
 	for (domain = 0; domain < ndomains; domain++) {
 		sbuf_printf(&sbuf, "\nDOMAIN %d:\n\n", domain);
 		for (flind = 0; flind < vm_nfreelists; flind++)
 			sbuf_printf(&sbuf, "  [%d]:\t%p\n", flind,
 			    vm_phys_lookup_lists[domain][flind]);
 	}
-	sbuf_finish(&sbuf);
-	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
+	error = sbuf_finish(&sbuf);
 	sbuf_delete(&sbuf);
-	free(cbuf, M_TEMP);
 	return (error);
 }
 #endif
diff --git a/sys/vm/vm_reserv.c b/sys/vm/vm_reserv.c
index d9e908f..aa8e80f 100644
--- a/sys/vm/vm_reserv.c
+++ b/sys/vm/vm_reserv.c
@@ -180,12 +180,9 @@ sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
 {
 	struct sbuf sbuf;
 	vm_reserv_t rv;
-	char *cbuf;
-	const int cbufsize = (VM_NRESERVLEVEL + 1) * 81;
 	int counter, error, level, unused_pages;
 
-	cbuf = malloc(cbufsize, M_TEMP, M_WAITOK | M_ZERO);
-	sbuf_new(&sbuf, cbuf, cbufsize, SBUF_FIXEDLEN);
+	sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
 	sbuf_printf(&sbuf, "\nLEVEL     SIZE  NUMBER\n\n");
 	for (level = -1; level <= VM_NRESERVLEVEL - 2; level++) {
 		counter = 0;
@@ -199,10 +196,8 @@ sysctl_vm_reserv_partpopq(SYSCTL_HANDLER_ARGS)
 		sbuf_printf(&sbuf, "%5.5d: %6.6dK, %6.6d\n", level,
 		    unused_pages * (PAGE_SIZE / 1024), counter);
 	}
-	sbuf_finish(&sbuf);
-	error = SYSCTL_OUT(req, sbuf_data(&sbuf), sbuf_len(&sbuf));
+	error = sbuf_finish(&sbuf);
 	sbuf_delete(&sbuf);
-	free(cbuf, M_TEMP);
 	return (error);
 }