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Date:      Sat, 31 Mar 2018 12:45:40 +0000 (UTC)
From:      Konstantin Belousov <kib@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org
Subject:   svn commit: r331841 - stable/11/sys/vm
Message-ID:  <201803311245.w2VCjeLp051699@repo.freebsd.org>
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Author: kib
Date: Sat Mar 31 12:45:39 2018
New Revision: 331841
URL: https://svnweb.freebsd.org/changeset/base/331841

Log:
  MFC r331489:
  For vm_zone_stats() sysctl handler, do not drain sbuf calling copyout(9)
  while owning zone lock.

Modified:
  stable/11/sys/vm/uma_core.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/vm/uma_core.c
==============================================================================
--- stable/11/sys/vm/uma_core.c	Sat Mar 31 12:44:11 2018	(r331840)
+++ stable/11/sys/vm/uma_core.c	Sat Mar 31 12:45:39 2018	(r331841)
@@ -3414,7 +3414,7 @@ sysctl_vm_zone_stats(SYSCTL_HANDLER_ARGS)
 {
 	struct uma_stream_header ush;
 	struct uma_type_header uth;
-	struct uma_percpu_stat ups;
+	struct uma_percpu_stat *ups;
 	uma_bucket_t bucket;
 	struct sbuf sbuf;
 	uma_cache_t cache;
@@ -3429,6 +3429,7 @@ sysctl_vm_zone_stats(SYSCTL_HANDLER_ARGS)
 		return (error);
 	sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
 	sbuf_clear_flags(&sbuf, SBUF_INCLUDENUL);
+	ups = malloc((mp_maxid + 1) * sizeof(*ups), M_TEMP, M_WAITOK);
 
 	count = 0;
 	rw_rlock(&uma_rwlock);
@@ -3477,7 +3478,6 @@ sysctl_vm_zone_stats(SYSCTL_HANDLER_ARGS)
 			uth.uth_frees = z->uz_frees;
 			uth.uth_fails = z->uz_fails;
 			uth.uth_sleeps = z->uz_sleeps;
-			(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
@@ -3486,30 +3486,31 @@ sysctl_vm_zone_stats(SYSCTL_HANDLER_ARGS)
 			 * accept the possible race associated with bucket
 			 * exchange during monitoring.
 			 */
-			for (i = 0; i < (mp_maxid + 1); i++) {
-				bzero(&ups, sizeof(ups));
-				if (kz->uk_flags & UMA_ZFLAG_INTERNAL)
-					goto skip;
-				if (CPU_ABSENT(i))
-					goto skip;
+			for (i = 0; i < mp_maxid + 1; i++) {
+				bzero(&ups[i], sizeof(*ups));
+				if (kz->uk_flags & UMA_ZFLAG_INTERNAL ||
+				    CPU_ABSENT(i))
+					continue;
 				cache = &z->uz_cpu[i];
 				if (cache->uc_allocbucket != NULL)
-					ups.ups_cache_free +=
+					ups[i].ups_cache_free +=
 					    cache->uc_allocbucket->ub_cnt;
 				if (cache->uc_freebucket != NULL)
-					ups.ups_cache_free +=
+					ups[i].ups_cache_free +=
 					    cache->uc_freebucket->ub_cnt;
-				ups.ups_allocs = cache->uc_allocs;
-				ups.ups_frees = cache->uc_frees;
-skip:
-				(void)sbuf_bcat(&sbuf, &ups, sizeof(ups));
+				ups[i].ups_allocs = cache->uc_allocs;
+				ups[i].ups_frees = cache->uc_frees;
 			}
 			ZONE_UNLOCK(z);
+			(void)sbuf_bcat(&sbuf, &uth, sizeof(uth));
+			for (i = 0; i < mp_maxid + 1; i++)
+				(void)sbuf_bcat(&sbuf, &ups[i], sizeof(ups[i]));
 		}
 	}
 	rw_runlock(&uma_rwlock);
 	error = sbuf_finish(&sbuf);
 	sbuf_delete(&sbuf);
+	free(ups, M_TEMP);
 	return (error);
 }

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