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author | Simon Rettberg | 2019-08-07 17:11:51 +0200 |
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committer | Simon Rettberg | 2019-08-07 17:11:51 +0200 |
commit | be7d7d95850c30a154aaa56e95d6a7f36793409d (patch) | |
tree | 53bcae440652076d53cb01bfb7ee73fc2d868283 /src/server/altservers.c | |
parent | [SERVER] Lock-free queue for altservers check thread (diff) | |
download | dnbd3-be7d7d95850c30a154aaa56e95d6a7f36793409d.tar.gz dnbd3-be7d7d95850c30a154aaa56e95d6a7f36793409d.tar.xz dnbd3-be7d7d95850c30a154aaa56e95d6a7f36793409d.zip |
[SERVER] Better lock debugging: Always check lock order
Lock order is predefined in locks.h. Immediately bail out if a lock with
lower priority is obtained while the same thread already holds one with
higher priority.
Diffstat (limited to 'src/server/altservers.c')
-rw-r--r-- | src/server/altservers.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/src/server/altservers.c b/src/server/altservers.c index a270bf3..3d5e71e 100644 --- a/src/server/altservers.c +++ b/src/server/altservers.c @@ -30,7 +30,7 @@ void altservers_init() { srand( (unsigned int)time( NULL ) ); // Init spinlock - mutex_init( &altServersLock ); + mutex_init( &altServersLock, LOCK_ALT_SERVER_LIST ); // Init signal runSignal = signal_new(); if ( runSignal == NULL ) { @@ -326,13 +326,13 @@ json_t* altservers_toJson() } /** - * Update rtt history of given server - returns the new average for that server + * Update rtt history of given server - returns the new average for that server. + * XXX HOLD altServersLock WHEN CALLING THIS! */ static unsigned int altservers_updateRtt(const dnbd3_host_t * const host, const unsigned int rtt) { unsigned int avg = rtt; int i; - mutex_lock( &altServersLock ); for (i = 0; i < numAltServers; ++i) { if ( !isSameAddressPort( host, &altServers[i].host ) ) continue; altServers[i].rtt[++altServers[i].rttIndex % SERVER_RTT_PROBES] = rtt; @@ -353,7 +353,6 @@ static unsigned int altservers_updateRtt(const dnbd3_host_t * const host, const } break; } - mutex_unlock( &altServersLock ); return avg; } @@ -529,6 +528,7 @@ static void *altservers_main(void *data UNUSED) } clock_gettime( BEST_CLOCK_SOURCE, &end ); // Measurement done - everything fine so far + mutex_lock( &altServersLock ); mutex_lock( &uplink->rttLock ); const bool isCurrent = isSameAddressPort( &servers[itAlt], &uplink->currentServer ); // Penaltize rtt if this was a cycle; this will treat this server with lower priority @@ -538,6 +538,7 @@ static void *altservers_main(void *data UNUSED) + (end.tv_nsec - start.tv_nsec) / 1000 + ( (isCurrent && uplink->cycleDetected) ? 1000000 : 0 )); // µs unsigned int avg = altservers_updateRtt( &servers[itAlt], rtt ); + mutex_unlock( &altServersLock ); // If a cycle was detected, or we lost connection to the current (last) server, penaltize it one time if ( ( uplink->cycleDetected || uplink->fd == -1 ) && isCurrent ) avg = (avg * 2) + 50000; mutex_unlock( &uplink->rttLock ); |