Foliensatz 5: Synchronisation. Hans-Georg Eßer, Hochschule München Betriebssysteme I, Sommersemester Folie 3. Foliensatz 5: Synchronisation

Transkript

1 Sep 19 14:20:18 amd64 sshd[20494]: Accepted rsa for esser from ::ffff: port Sep 19 14:27:41 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 01:00:01 amd64 /usr/sbin/cron[29278]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 20 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 02:00:01 amd64 /usr/sbin/cron[30103]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 20 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 12:46:44 amd64 sshd[6516]: Accepted rsa for esser from ::ffff: port Sep 20 12:46:44 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 12:48:41 amd64 sshd[6609]: Accepted rsa for esser from ::ffff: port Sep 20 12:54:44 amd64 sshd[6694]: Accepted rsa for esser from ::ffff: port Sep 20 15:27:35 amd64 sshd[9077]: Accepted rsa for esser from ::ffff: port Sep 20 15:27:35 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 16:37:11 amd64 sshd[10102]: Accepted rsa for esser from ::ffff: port Sep 20 16:37:11 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 16:38:10 amd64 sshd[10140]: Accepted rsa for esser from ::ffff: port Sep 21 01:00:01 amd64 /usr/sbin/cron[17055]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 21 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 02:00:01 amd64 /usr/sbin/cron[17878]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 21 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 17:43:26 amd64 sshd[31088]: Accepted rsa for esser from ::ffff: port Sep 21 17:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 17:53:39 amd64 sshd[31269]: Accepted rsa for esser from ::ffff: port Sep 21 18:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 19:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 01:00:01 amd64 /usr/sbin/cron[4674]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 22 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 02:00:01 amd64 /usr/sbin/cron[5499]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 22 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 20:23:21 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 01:00:01 amd64 /usr/sbin/cron[24739]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 23 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 02:00:01 amd64 /usr/sbin/cron[25555]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 23 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 18:04:05 amd64 sshd[6554]: Accepted publickey for esser from ::ffff: port ssh2 Sep 23 18:04:05 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 18:04:34 amd64 sshd[6606]: Accepted rsa for esser from ::ffff: port Sep 24 01:00:01 amd64 /usr/sbin/cron[12436]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 24 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 02:00:01 amd64 /usr/sbin/cron[13253]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 24 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 11:15:48 amd64 sshd[20998]: Accepted rsa for esser from ::ffff: port Sep 24 11:15:48 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 13:49:08 amd64 sshd[23197]: Accepted rsa for esser from ::ffff: port Sep 24 13:49:08 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 15:42:07 amd64 kernel: snd_seq_midi_event: unsupported module, tainting kernel. Sep 24 15:42:07 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 15:42:07 amd64 kernel: snd_seq_oss: unsupported module, tainting kernel. Sep 24 20:25:31 amd64 sshd[29399]: Accepted rsa for esser from ::ffff: port Sep 24 20:25:31 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 01:00:02 amd64 /usr/sbin/cron[662]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 25 01:00:02 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 02:00:01 amd64 /usr/sbin/cron[1484]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 25 02:00:02 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 10:59:25 amd64 sshd[8889]: Accepted rsa for esser from ::ffff: port Sep 25 10:59:25 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 10:59:47 amd64 sshd[8921]: Accepted rsa for esser from ::ffff: port Sep 25 11:30:02 amd64 sshd[9372]: Accepted rsa for esser from ::ffff: port Sep 25 11:59:25 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 14:05:37 amd64 sshd[11554]: Accepted rsa for esser from ::ffff: port Sep 25 14:05:37 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 14:06:10 amd64 sshd[11586]: Accepted rsa for esser from ::ffff: port Sep 25 14:07:17 amd64 sshd[11608]: Accepted rsa for esser from ::ffff: port Sep 25 14:08:33 amd64 sshd[11630]: Accepted rsa for esser from ::ffff: port Sep 25 15:25:33 amd64 sshd[12930]: Accepted rsa for esser from ::ffff: port Folie 3 Folie 2 Folie 4

2 erhoehe_zaehler() Folie 5 Folie 7 exec sql CONNECT... exec sql SELECT kontostand INTO $var FROM KONTO WHERE kontonummer = $knr $var = $var - abhebung exec sql UPDATE Konto SET kontostand = $var WHERE kontonummer = $knr exec sql DISCONNECT Folie 6 Folie 8

3 read(command) f=open("/tmp/script","w") write(f,command) f.close() chmod("/tmp/script","a+x") system("/tmp/script") Folie 9 Folie 11 erhoehe_zaehler( ) { flag=read(lock); if (flag == LOCK_UNSET) { set(lock); /* Anfang des kritischen Bereichs */ w=read(adresse); w=w+1; write(adresse,w); /* Ende des kritischen Bereichs */ release(lock); ; Folie 10 Folie 12

4 Folie 13 Folie 15 while ( lock ) { /* warten */ ; lock=true; kritischer_bereich(); lock=false; Folie 14 Folie 16

5 Folie 17 while (true) { while (true) { C1=true; C2=true; while (C2) { while (C1) { if (turn!= 1) { if (turn!= 2) { C1=false; C2=false; while (turn!= 1) { while (turn!= 2) { /* wait */ /* wait */ ; ; C1=true; C2=true; ; ; ; ; kritischer_bereich(); kritischer_bereich(); turn=2; turn=1; C1=false; C2=false; Folie 19 while (true) { while (true) { C1=true; C2=true; while (C2) { while (C1) { /* wait */ /* wait */ ; ; kritischer_bereich(); kritischer_bereich(); C1=false; C2=false; C1=true; C2=true; turn=2; turn=1; while (C2 && turn==2) while (C1 && turn==1) /* warten */; /* warten */; kritischer_abschnitt(); kritischer_abschnitt(); C1=false; C2=false; Folie 18 Folie 20

6 enter: tsl register, flag ; Variablenwert in Register kopieren und ; dann Variable auf 1 setzen cmp register, 0 ; War die Variable 0? jnz enter ; Nicht 0: Lock war gesetzt, also Schleife ret leave: mov flag, 0 ret ; 0 in flag speichern: Lock freigeben Folie 21 Folie 23 Folie 22 Folie 24

7 nächste Schreib-Position Folie 25 nächste Lese-Position Folie 27 Folie 26 Folie 28

8 Folie 29 Folie 31 #define N 100 int count = 0; // Anzahl der Plätze im Puffer // Anzahl der belegten Plätze im Puffer producer () { while (TRUE) { // Endlosschleife produce_item (item); // Erzeuge etwas für den Puffer if (count == N) sleep(); // Wenn Puffer voll: schlafen legen enter_item (item); // In den Puffer einstellen count = count + 1; // Zahl der belegten Plätze inkrementieren if (count == 1) wake(consumer); // war der Puffer vorher leer? consumer () { while (TRUE) { // Endlosschleife if (count == 0) sleep(); // Wenn Puffer leer: schlafen legen remove_item (item); // Etwas aus dem Puffer entnehmen count = count - 1; // Zahl der belegten Plätze dekrementieren if (count == N-1) wake(producer); // war der Puffer vorher voll? consume_item (item); // Verarbeiten Folie 30 VERBRAUCHER n=read(count); /* n=0 */ sleep(); ERZEUGER.. produce_item(); n=read(count); /* n=0 */ n=n+1; write(n,count); wake(verbraucher);.... Folie 32

9 wait (&sem); /* Code, der die Ressource nutzt */ signal (&sem); Folie 33 Folie 35 Folie 34 Folie 36

10 wait (sem) { if (sem>0) sem--; else BLOCK_CALLER; wait (sem) { if (sem<1) BLOCK_CALLER; sem--; signal (sem) { if (P in QUEUE(sem)) { wakeup (P); remove (P, QUEUE); else sem++; signal (sem) { if (P in QUEUE(sem)) { wakeup (P); remove (P, QUEUE); sem++; wait (mutex) { if (mutex==1) mutex=0; else BLOCK_CALLER; signal (mutex) { if (P in QUEUE(mutex)) { wakeup (P); remove (P, QUEUE); else mutex=1; Folie 37 Folie 39 Folie 38 Folie 40

11 Folie 41 typedef int semaphore; semaphore mutex = 1; semaphore empty = N; semaphore full = 0; producer() { while (TRUE) { produce_item(item); wait (empty); wait (mutex); enter_item (item); signal (mutex); signal (full); // Kontrolliert Zugriff auf Puffer // Zählt freie Plätze im Puffer // Zählt belegte Plätze im Puffer // Endlosschleife // Erzeuge etwas für den Puffer // Leere Plätze dekrementieren bzw. blockieren // Eintritt in den kritischen Bereich // In den Puffer einstellen // Kritischen Bereich verlassen // Belegte Plätze erhöhen, evtl. consumer wecken consumer() { while (TRUE) { // Endlosschleife wait (full); // Belegte Plätze dekrementieren bzw. blockieren wait (mutex); // Eintritt in den kritischen Bereich remove_item(item); // Aus dem Puffer entnehmen signal (mutex); // Kritischen Bereich verlassen signal (empty); // Freie Plätze erhöhen, evtl. producer wecken consume_entry (item); // Verbrauchen Folie 43 Folie 42 Folie 44

12 Folie 45 mutex disk_access = 1; monitor disk { entry read (diskaddr, memaddr) { // Daten von der Platte lesen ; entry write (diskaddr, memaddr) { // Daten auf die Platte schreiben ; init () { // Gerät initialisieren ; ; wait (disk_access); // Daten von der Platte lesen signal (disk_access); wait (disk_access); // Daten auf die Platte schreiben signal (disk_access); disk.read (da, ma); disk.write (da, ma); Folie krit_1(); krit_1();... entry funktion () { void funktion () { /* Code */ wait (m_disk); /* Code */ signal (m_disk); disk.funktion(); funktion(); Folie 46 Folie 48

13 Folie 49 f() m_wait(cv) g() m_signal(cv) Zeit Folie 51 Folie 50 conditionvariable { int queuesize = 0; mutex m; semaphore waiting; wait() { m.lock(); queuesize++; m.release(); waiting.down(); signal() { m.lock(); while (queuesize > 0){ // alle wecken queuesize--; waiting.up(); m.release(); Folie 52

14 Erzeuger- Verbraucher- Problem mit Monitor Quelle: Prof. Scheidig, Univ. Saarbrücken, WS0607/Vorlesung_Betriebssysteme/ - angepasst an C-artige Syntax monitor iostream { item buffer; int count; const int bufsize = 64; condition nonempty, nonfull; entry append(item x) { while (count == bufsize) m_wait(nonfull); put(buffer, x); // put ist lokale Prozedur count = 1; m_signal(nonempty); entry remove(item x) { while (count == 0) m_wait(nonempty); get(buffer, x); // get ist lokale Prozedur count = 0; m_signal(nonfull); init() { count = 0; // Initialisierung Folie 53 Quelle: ConcProgJava/Monitors/bbse.java class BoundedBuffer extends MyObject { private int size = 0; private double[] buf = null; private int front = 0, rear = 0, count = 0; public BoundedBuffer(int size) { this.size = size; buf = new double[size]; public synchronized void deposit(double data) { while (count == size) wait(); buf[rear] = data; rear = (rear+1) % size; count++; if (count == 1) notify(); public synchronized double fetch() { double result; while (count == 0) wait(); result = buf[front]; front = (front+1) % size; count--; if (count == size-1) notify(); return result; Folie 55 Folie 54 Folie 56

15 send (destination, &message); receive (source, &message); Folie 57 Folie 59 Folie 58 Folie 60

16 Folie 61 Sep 19 14:20:18 amd64 sshd[20494]: Accepted rsa for esser from ::ffff: port Sep 19 14:27:41 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 01:00:01 amd64 /usr/sbin/cron[29278]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 20 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 02:00:01 amd64 /usr/sbin/cron[30103]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 20 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 12:46:44 amd64 sshd[6516]: Accepted rsa for esser from ::ffff: port Sep 20 12:46:44 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 12:48:41 amd64 sshd[6609]: Accepted rsa for esser from ::ffff: port Sep 20 12:54:44 amd64 sshd[6694]: Accepted rsa for esser from ::ffff: port Sep 20 15:27:35 amd64 sshd[9077]: Accepted rsa for esser from ::ffff: port Sep 20 15:27:35 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 16:37:11 amd64 sshd[10102]: Accepted rsa for esser from ::ffff: port Sep 20 16:37:11 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 16:38:10 amd64 sshd[10140]: Accepted rsa for esser from ::ffff: port Sep 21 01:00:01 amd64 /usr/sbin/cron[17055]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 21 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 02:00:01 amd64 /usr/sbin/cron[17878]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 21 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 17:43:26 amd64 sshd[31088]: Accepted rsa for esser from ::ffff: port Sep 21 17:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 17:53:39 amd64 sshd[31269]: Accepted rsa for esser from ::ffff: port Sep 21 18:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 19:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 01:00:01 amd64 /usr/sbin/cron[4674]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 22 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 02:00:01 amd64 /usr/sbin/cron[5499]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 22 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 20:23:21 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 01:00:01 amd64 /usr/sbin/cron[24739]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 23 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 02:00:01 amd64 /usr/sbin/cron[25555]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 23 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 18:04:05 amd64 sshd[6554]: Accepted publickey for esser from ::ffff: port ssh2 Sep 23 18:04:05 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 18:04:34 amd64 sshd[6606]: Accepted rsa for esser from ::ffff: port Sep 24 01:00:01 amd64 /usr/sbin/cron[12436]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 24 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 02:00:01 amd64 /usr/sbin/cron[13253]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 24 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 11:15:48 amd64 sshd[20998]: Accepted rsa for esser from ::ffff: port Sep 24 11:15:48 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 13:49:08 amd64 sshd[23197]: Accepted rsa for esser from ::ffff: port Sep 24 13:49:08 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 15:42:07 amd64 kernel: snd_seq_midi_event: unsupported module, tainting kernel. Sep 24 15:42:07 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 15:42:07 amd64 kernel: snd_seq_oss: unsupported module, tainting kernel. Sep 24 20:25:31 amd64 sshd[29399]: Accepted rsa for esser from ::ffff: port Sep 24 20:25:31 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 01:00:02 amd64 /usr/sbin/cron[662]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 25 01:00:02 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 02:00:01 amd64 /usr/sbin/cron[1484]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 25 02:00:02 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 10:59:25 amd64 sshd[8889]: Accepted rsa for esser from ::ffff: port Sep 25 10:59:25 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 10:59:47 amd64 sshd[8921]: Accepted rsa for esser from ::ffff: port Sep 25 11:30:02 amd64 sshd[9372]: Accepted rsa for esser from ::ffff: port Sep 25 11:59:25 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 14:05:37 amd64 sshd[11554]: Accepted rsa for esser from ::ffff: port Sep 25 14:05:37 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 14:06:10 amd64 sshd[11586]: Accepted rsa for esser from ::ffff: port Sep 25 14:07:17 amd64 sshd[11608]: Accepted rsa for esser from ::ffff: port Sep 25 14:08:33 amd64 sshd[11630]: Accepted rsa for esser from ::ffff: port Sep 25 15:25:33 amd64 sshd[12930]: Accepted rsa for esser from ::ffff: port void funktion (int id) { int otherid = 1 id; char message[10] = ""; // ein Prozess darf zuerst; ID 0 if (id==0) { message = "go"; // unkritische Befehle while message!= "go" { receive (otherid, &message); // kritischer Bereich send (otherid, "go"); message = ""; // mehr unkritische Befehle Folie 62 Folie 64

17 Folie 65 Folie 67 Folie 66 Folie 68

18 spinlock_t xy_lock = SPIN_LOCK_UNLOCKED unsigned long flags; spin_lock_irqsave (&xy_lock, flags); /* kritischer Abschnitt */ spin_unlock_irqrestore (&xy_lock, flags); Folie 69 Folie 71 spinlock_t xy_lock = SPIN_LOCK_UNLOCKED spin_lock (&xy_lock); /* kritischer Abschnitt */ spin_unlock (&xy_lock); Folie 70 spinlock_t xy_lock = SPIN_LOCK_UNLOCKED spin_lock_irq (&xy_lock); /* kritischer Abschnitt */ spin_unlock_irq (&xy_lock); Folie 72

19 read_lock(&lck) write_lock(&lck) if ( spin_try_lock (&xy_lock) ) { /* kritischer Abschnitt */ spin_unlock (&xy_lock); else { /* durfte nicht in den kritischen Abschnitt */ Folie 73 Folie 75 rwlock_t xy_rwlock = RW_LOCK_UNLOCKED; read_lock (&xy_rwlock) ) { /* kritischer Abschnitt, read-only */ read_unlock (&xy_rwlock); write_lock (&xy_rwlock) ) { /* kritischer Abschnitt, read & write */ write_unlock (&xy_rwlock); Folie 74 Folie 76

20 Folie 77 Folie 79 static DECLARE_SEMAPHORE_GENERIC (name, count); static DECLARE_MUTEX (name); /* count=1 */ sema_init (&sem,count); init_mutex (&sem); /* count=1 */ down (&sem); /* kritischer Abschnitt */ up (&sem); Folie 78 /* Auszug aus /usr/src/linux/kernel/printk.c */ if (!down_trylock(&console_sem)) { console_locked = 1; /* * We own the drivers. We can drop the spinlock and let * release_console_sem() print the text */ spin_unlock_irqrestore(&logbuf_lock, flags); console_may_schedule = 0; release_console_sem(); /* Funktion release_console_sem() führt up(&console_sem); aus */ else { /* * Someone else owns the drivers. We drop the spinlock, which * allows the semaphore holder to proceed and to call the * console drivers with the output which we just produced. */ spin_unlock_irqrestore(&logbuf_lock, flags); Folie 80

21 static DECLARE_RWSEM (name); init_rwsem (&sem); Folie 81 Sep 19 14:20:18 amd64 sshd[20494]: Accepted rsa for esser from ::ffff: port Sep 19 14:27:41 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 01:00:01 amd64 /usr/sbin/cron[29278]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 20 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 02:00:01 amd64 /usr/sbin/cron[30103]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 20 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 12:46:44 amd64 sshd[6516]: Accepted rsa for esser from ::ffff: port Sep 20 12:46:44 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 12:48:41 amd64 sshd[6609]: Accepted rsa for esser from ::ffff: port Sep 20 12:54:44 amd64 sshd[6694]: Accepted rsa for esser from ::ffff: port Sep 20 15:27:35 amd64 sshd[9077]: Accepted rsa for esser from ::ffff: port Sep 20 15:27:35 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 16:37:11 amd64 sshd[10102]: Accepted rsa for esser from ::ffff: port Sep 20 16:37:11 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 20 16:38:10 amd64 sshd[10140]: Accepted rsa for esser from ::ffff: port Sep 21 01:00:01 amd64 /usr/sbin/cron[17055]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 21 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 02:00:01 amd64 /usr/sbin/cron[17878]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 21 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 17:43:26 amd64 sshd[31088]: Accepted rsa for esser from ::ffff: port Sep 21 17:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 17:53:39 amd64 sshd[31269]: Accepted rsa for esser from ::ffff: port Sep 21 18:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 21 19:43:26 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 01:00:01 amd64 /usr/sbin/cron[4674]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 22 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 02:00:01 amd64 /usr/sbin/cron[5499]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 22 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 22 20:23:21 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 01:00:01 amd64 /usr/sbin/cron[24739]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 23 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 02:00:01 amd64 /usr/sbin/cron[25555]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 23 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 18:04:05 amd64 sshd[6554]: Accepted publickey for esser from ::ffff: port ssh2 Sep 23 18:04:05 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 23 18:04:34 amd64 sshd[6606]: Accepted rsa for esser from ::ffff: port Sep 24 01:00:01 amd64 /usr/sbin/cron[12436]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 24 01:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 02:00:01 amd64 /usr/sbin/cron[13253]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 24 02:00:01 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 11:15:48 amd64 sshd[20998]: Accepted rsa for esser from ::ffff: port Sep 24 11:15:48 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 13:49:08 amd64 sshd[23197]: Accepted rsa for esser from ::ffff: port Sep 24 13:49:08 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 15:42:07 amd64 kernel: snd_seq_midi_event: unsupported module, tainting kernel. Sep 24 15:42:07 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 24 15:42:07 amd64 kernel: snd_seq_oss: unsupported module, tainting kernel. Sep 24 20:25:31 amd64 sshd[29399]: Accepted rsa for esser from ::ffff: port Sep 24 20:25:31 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 01:00:02 amd64 /usr/sbin/cron[662]: (root) CMD (/sbin/evlogmgr -c "severity=debug") Sep 25 01:00:02 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 02:00:01 amd64 /usr/sbin/cron[1484]: (root) CMD (/sbin/evlogmgr -c 'age > "30d"') Sep 25 02:00:02 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 10:59:25 amd64 sshd[8889]: Accepted rsa for esser from ::ffff: port Sep 25 10:59:25 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 10:59:47 amd64 sshd[8921]: Accepted rsa for esser from ::ffff: port Sep 25 11:30:02 amd64 sshd[9372]: Accepted rsa for esser from ::ffff: port Sep 25 11:59:25 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 14:05:37 amd64 sshd[11554]: Accepted rsa for esser from ::ffff: port Sep 25 14:05:37 amd64 syslog-ng[7653]: STATS: dropped 0 Sep 25 14:06:10 amd64 sshd[11586]: Accepted rsa for esser from ::ffff: port Sep 25 14:07:17 amd64 sshd[11608]: Accepted rsa for esser from ::ffff: port Sep 25 14:08:33 amd64 sshd[11630]: Accepted rsa for esser from ::ffff: port Sep 25 15:25:33 amd64 sshd[12930]: Accepted rsa for esser from ::ffff: port static DECLARE_RWSEM (xy_rwsem); down_read (&xy_rwsem) ) { /* kritischer Abschnitt, read-only */ up_read (&xy_rwsem); down_write (&xy_rwsem) ) { /* kritischer Abschnitt, lesen und schreiben */ up_write (&xy_rwsem); down_read(&sem) down_write(&sem) Folie 82 Folie 84

22 Folie 85 Folie 87 Folie 86 Folie 88

23 Q: wagen_4 () { lock(b); lock(c); go(); unlock(b); unlock(c); wagen_3 () { lock(a); lock(b); go(); unlock(a); unlock(b); wagen_1 () { lock(c); lock(d); go(); unlock(c); unlock(d); wagen_2 () { lock(d); lock(a); go(); unlock(d); unlock(a); lock (B); lock (A); /* krit. Bereich */ unlock (B); unlock (A); unlock(a) unlock(b) lock(a) lock(b) Folie 89 Folie 91 lock (A); lock (B); /* krit. Bereich */ unlock (A); unlock (B); lock (B); lock (A); /* krit. Bereich */ unlock (B); unlock (A); Programmverzahnungen, die zwangsläufig in den Deadlock führen: oberer roter Weg: Q: lock(b) P: lock(a) unterer roter Weg: P: lock(a) Q: lock(b) Folie 90 Folie 92

24 lock (A); /* krit. Bereich */ unlock (A); lock (B); /* krit. Bereich */ unlock (B); lock (B); lock (A); /* krit. Bereich */ unlock (B); unlock (A); Folie 93 Folie 95 Q: lock (B); lock (A); /* krit. Bereich */ unlock (B); unlock (A); unlock(a) unlock(b) lock(a) lock(b) Folie 94 Folie 96

25 Folie 97 Folie 99 Folie 98 Folie 100

26 Folie 101 Folie 103 Folie 102 Folie 104

27 Folie 105 Folie 107 Folie 106 Folie 108

28 Folie 109 Folie 111 Folie 110 Folie 112

29 Folie 113 Folie 115 Folie 114 Folie 116

30 Folie 117 Folie 119 Folie 118 Folie 120

31 1 E = ( ) C' = A' = ( ) R' = E = ( ) C' = A' = ( ) R' = E = ( ) C' = A' = ( ) R' = E = ( ) C' = A' = ( ) R' = Folie E = ( ) C' = R' = A' = ( ) E = ( ) C' = A' = ( ) R' = Folie 123 C = E = ( ) => A = ( ) Max = C' = E = ( ) => A' = ( ) R' = R=Max-C = Folie 122 Folie 124

32 Folie 125 Folie 127 Folie 126 lock (S); lock (R); Folie 128

33 Folie 129