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Fix possible deadlock on SMP stop_this_cpu 

Do not use printk on the running thread after it has been sent
the INIT IPI, execution may halt with console spinlock held.

Change-Id: I64608935ea740fb827fa0307442f3fb102de7a08
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/776
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Rudolf Marek <r.marek@assembler.cz>
This commit is contained in:
Kyösti Mälkki 2012-03-04 02:24:36 +02:00 committed by Rudolf Marek
parent 8b28d50cdd
commit a01ae624af
1 changed files with 25 additions and 4 deletions
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29
src/cpu/x86/lapic/lapic_cpu_init.c
View File

@ -277,6 +277,19 @@ int start_cpu(device_t cpu)
}
#if CONFIG_AP_IN_SIPI_WAIT == 1
/**
* Sending INIT IPI to self is equivalent of asserting #INIT with a bit of delay.
* An undefined number of instruction cycles will complete. All global locks
* must be released before INIT IPI and no printk is allowed after this.
* De-asserting INIT IPI is a no-op on later Intel CPUs.
*
* If you set DEBUG_HALT_SELF to 1, printk's after INIT IPI are enabled
* but running thread may halt without releasing the lock and effectively
* deadlock other CPUs.
*/
#define DEBUG_HALT_SELF 0
/**
* Normally this function is defined in lapic.h as an always inline function
* that just keeps the CPU in a hlt() loop. This does not work on all CPUs.
@ -298,38 +311,46 @@ void stop_this_cpu(void)
lapic_write_around(LAPIC_ICR, LAPIC_INT_LEVELTRIG | LAPIC_INT_ASSERT | LAPIC_DM_INIT);
/* wait for the ipi send to finish */
#if 0
// When these two printk(BIOS_SPEW, ...) calls are not removed, the
// machine will hang when log level is SPEW. Why?
#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "Waiting for send to finish...\n");
#endif
timeout = 0;
do {
#if 0
#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "+");
#endif
udelay(100);
send_status = lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY;
} while (send_status && (timeout++ < 1000));
if (timeout >= 1000) {
#if DEBUG_HALT_SELF
printk(BIOS_ERR, "timed out\n");
#endif
}
mdelay(10);
#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "Deasserting INIT.\n");
#endif
/* Deassert the LAPIC INIT */
lapic_write_around(LAPIC_ICR2, SET_LAPIC_DEST_FIELD(id));
lapic_write_around(LAPIC_ICR, LAPIC_INT_LEVELTRIG | LAPIC_DM_INIT);
#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "Waiting for send to finish...\n");
#endif
timeout = 0;
do {
#if DEBUG_HALT_SELF
printk(BIOS_SPEW, "+");
#endif
udelay(100);
send_status = lapic_read(LAPIC_ICR) & LAPIC_ICR_BUSY;
} while (send_status && (timeout++ < 1000));
if (timeout >= 1000) {
#if DEBUG_HALT_SELF
printk(BIOS_ERR, "timed out\n");
#endif
}
while(1) {