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runq_lock: Fix deadlock due to cpu migration.

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Symptom and analysis:
runq_lock of the migration source is acquired on
the migration destination CPU.

This happens in the following steps:
 (1) The thread stores value of cpu_local_var(runq_lock)
     to its register when trying to perform
     ihk_mc_spinlock_lock() on the lock variable.
 (2) The thread takes IPI and migrates to another CPU.
 (3) The thread resumes execution and acquires the wrong lock.

Solution:
* Disable interrupts before getting the value of
  cpu_local_var(runq_lock)

Change-Id: Ia0ea450b97f872dd6116252537e4a79f85adfc88
Refs: #1400
This commit is contained in:
Shiratori, Takehiro
2020-02-13 13:02:40 +09:00
committed by Masamichi Takagi
parent 1a204b6674
commit edf7b36669
4 changed files with 38 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
arch/arm64/kernel/syscall.c
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@ -1448,7 +1448,9 @@ __check_signal(unsigned long rc, void *regs0, int num, int irq_disabled)
if(thread == NULL || thread->proc->pid == 0){
struct thread *t;
irqstate = ihk_mc_spinlock_lock(&(cpu_local_var(runq_lock)));
irqstate = cpu_disable_interrupt_save();
ihk_mc_spinlock_lock_noirq(&(cpu_local_var(runq_lock)));
list_for_each_entry(t, &(cpu_local_var(runq)), sched_list){
if(t->proc->pid <= 0)
continue;
@ -1458,7 +1460,8 @@ __check_signal(unsigned long rc, void *regs0, int num, int irq_disabled)
break;
}
}
ihk_mc_spinlock_unlock(&(cpu_local_var(runq_lock)), irqstate);
ihk_mc_spinlock_unlock_noirq(&(cpu_local_var(runq_lock)));
cpu_restore_interrupt(irqstate);
goto out;
}