diff options
Diffstat (limited to 'src/backend/utils/misc/guc.c')
| -rw-r--r-- | src/backend/utils/misc/guc.c | 40 |
1 files changed, 22 insertions, 18 deletions
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 97ed5b72474..dac704ee4cd 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -10,7 +10,7 @@ * Written by Peter Eisentraut <peter_e@gmx.net>. * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.566 2010/08/06 14:51:33 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.567 2010/08/13 20:10:53 rhaas Exp $ * *-------------------------------------------------------------------- */ @@ -96,6 +96,16 @@ #define MAX_KILOBYTES (INT_MAX / 1024) #endif +/* + * Note: MAX_BACKENDS is limited to 2^23-1 because inval.c stores the + * backend ID as a 3-byte signed integer. Even if that limitation were + * removed, we still could not exceed INT_MAX/4 because some places compute + * 4*MaxBackends without any overflow check. This is rechecked in + * assign_maxconnections, since MaxBackends is computed as MaxConnections + * plus autovacuum_max_workers plus one (for the autovacuum launcher). + */ +#define MAX_BACKENDS 0x7fffff + #define KB_PER_MB (1024) #define KB_PER_GB (1024*1024) @@ -1414,23 +1424,13 @@ static struct config_int ConfigureNamesInt[] = 30 * 1000, -1, INT_MAX / 1000, NULL, NULL }, - /* - * Note: MaxBackends is limited to INT_MAX/4 because some places compute - * 4*MaxBackends without any overflow check. This check is made in - * assign_maxconnections, since MaxBackends is computed as MaxConnections - * plus autovacuum_max_workers plus one (for the autovacuum launcher). - * - * Likewise we have to limit NBuffers to INT_MAX/2. - * - * See also CheckRequiredParameterValues() if this parameter changes - */ { {"max_connections", PGC_POSTMASTER, CONN_AUTH_SETTINGS, gettext_noop("Sets the maximum number of concurrent connections."), NULL }, &MaxConnections, - 100, 1, INT_MAX / 4, assign_maxconnections, NULL + 100, 1, MAX_BACKENDS, assign_maxconnections, NULL }, { @@ -1439,9 +1439,13 @@ static struct config_int ConfigureNamesInt[] = NULL }, &ReservedBackends, - 3, 0, INT_MAX / 4, NULL, NULL + 3, 0, MAX_BACKENDS, NULL, NULL }, + /* + * We sometimes multiply the number of shared buffers by two without + * checking for overflow, so we mustn't allow more than INT_MAX / 2. + */ { {"shared_buffers", PGC_POSTMASTER, RESOURCES_MEM, gettext_noop("Sets the number of shared memory buffers used by the server."), @@ -1618,7 +1622,7 @@ static struct config_int ConfigureNamesInt[] = NULL }, &max_prepared_xacts, - 0, 0, INT_MAX / 4, NULL, NULL + 0, 0, MAX_BACKENDS, NULL, NULL }, #ifdef LOCK_DEBUG @@ -1782,7 +1786,7 @@ static struct config_int ConfigureNamesInt[] = NULL }, &max_wal_senders, - 0, 0, INT_MAX / 4, NULL, NULL + 0, 0, MAX_BACKENDS, NULL, NULL }, { @@ -2022,7 +2026,7 @@ static struct config_int ConfigureNamesInt[] = NULL }, &autovacuum_max_workers, - 3, 1, INT_MAX / 4, assign_autovacuum_max_workers, NULL + 3, 1, MAX_BACKENDS, assign_autovacuum_max_workers, NULL }, { @@ -7995,7 +7999,7 @@ show_tcp_keepalives_count(void) static bool assign_maxconnections(int newval, bool doit, GucSource source) { - if (newval + autovacuum_max_workers + 1 > INT_MAX / 4) + if (newval + autovacuum_max_workers + 1 > MAX_BACKENDS) return false; if (doit) @@ -8007,7 +8011,7 @@ assign_maxconnections(int newval, bool doit, GucSource source) static bool assign_autovacuum_max_workers(int newval, bool doit, GucSource source) { - if (MaxConnections + newval + 1 > INT_MAX / 4) + if (MaxConnections + newval + 1 > MAX_BACKENDS) return false; if (doit) |