diff --git a/arch/arm/src/armv7-a/arm_schedulesigaction.c b/arch/arm/src/armv7-a/arm_schedulesigaction.c index 9f1a46f6754..2bb30374a39 100644 --- a/arch/arm/src/armv7-a/arm_schedulesigaction.c +++ b/arch/arm/src/armv7-a/arm_schedulesigaction.c @@ -1,7 +1,7 @@ /**************************************************************************** * arch/arm/src/armv7-a/arm_schedulesigaction.c * - * Copyright (C) 2013, 2015-2017 Gregory Nutt. All rights reserved. + * Copyright (C) 2013, 2015-2018 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without @@ -116,7 +116,7 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) if (tcb == this_task()) { /* CASE 1: We are not in an interrupt handler and a task is - * signalling itself for some reason. + * signaling itself for some reason. */ if (!CURRENT_REGS) @@ -133,7 +133,7 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) * * Hmmm... there looks like a latent bug here: The following logic * would fail in the strange case where we are in an interrupt - * handler, the thread is signalling itself, but a context switch + * handler, the thread is signaling itself, but a context switch * to another task has occurred so that CURRENT_REGS does not * refer to the thread of this_task()! */ @@ -166,7 +166,7 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) /* Otherwise, we are (1) signaling a task is not running from an * interrupt handler or (2) we are not in an interrupt handler and the - * running task is signalling some other non-running task. + * running task is signaling some other non-running task. */ else @@ -222,7 +222,7 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) cpu = tcb->cpu; /* CASE 1: We are not in an interrupt handler and a task is - * signalling itself for some reason. + * signaling itself for some reason. */ if (cpu == me && !CURRENT_REGS) @@ -238,51 +238,36 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) * CPU. In the former case, we will have to PAUSE the other CPU * first. But in either case, we will have to modify the return * state as well as the state in the TCB. - * - * Hmmm... there looks like a latent bug here: The following logic - * would fail in the strange case where we are in an interrupt - * handler, the thread is signalling itself, but a context switch - * to another task has occurred so that CURRENT_REGS does not - * refer to the thread of this_task()! */ else { - /* If we signalling a task running on the other CPU, we have + /* If we signaling a task running on the other CPU, we have * to PAUSE the other CPU. */ if (cpu != me) { + /* Pause the CPU */ + up_cpu_pause(cpu); - } - /* Save the return lr and cpsr and one scratch register - * These will be restored by the signal trampoline after - * the signals have been delivered. - */ + /* Wait while the pause request is pending */ - tcb->xcp.sigdeliver = sigdeliver; - tcb->xcp.saved_pc = CURRENT_REGS[REG_PC]; - tcb->xcp.saved_cpsr = CURRENT_REGS[REG_CPSR]; + while (up_cpu_pausereq(cpu)) + { + } - /* Increment the IRQ lock count so that when the task is restarted, - * it will hold the IRQ spinlock. - */ + /* Now tcb on the other CPU can be accessed safely */ - DEBUGASSERT(tcb->irqcount < INT16_MAX); - tcb->irqcount++; + /* Copy tcb->xcp.regs to tcp.xcp.saved. These will be restored + * by the signal trampoline after the signal has been delivered. + */ - /* Handle a possible race condition where the TCB was suspended - * just before we paused the other CPU. The critical section - * established above will prevent new threads from running on - * that CPU, but it will not guarantee that the running thread - * did not suspend itself (allowing any threads "assigned" to - * the CPU to run). - */ + tcb->xcp.sigdeliver = sigdeliver; + tcb->xcp.saved_pc = tcb->xcp.regs[REG_PC]; + tcb->xcp.saved_cpsr = tcb->xcp.regs[REG_CPSR]; - if (tcb->task_state != TSTATE_TASK_RUNNING) - { /* Then set up to vector to the trampoline with interrupts * disabled */ @@ -292,23 +277,26 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) } else { - /* Then set up to vector to the trampoline with interrupts - * disabled + /* tcb is running on the same CPU */ + + /* Save the return PC, CPSR and either the BASEPRI or PRIMASK + * registers (and perhaps also the LR). These will be + * restored by the signal trampoline after the signal has been + * delivered. + */ + + tcb->xcp.sigdeliver = (FAR void *)sigdeliver; + tcb->xcp.saved_pc = CURRENT_REGS[REG_PC]; + tcb->xcp.saved_cpsr = CURRENT_REGS[REG_CPSR]; + + /* Then set up vector to the trampoline with interrupts + * disabled. The kernel-space trampoline must run in + * privileged thread mode. */ CURRENT_REGS[REG_PC] = (uint32_t)up_sigdeliver; CURRENT_REGS[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT | PSR_F_BIT); - /* In an SMP configuration, the interrupt disable logic also - * involves spinlocks that are configured per the TCB irqcount - * field. This is logically equivalent to enter_critical_section(). - * The matching call to leave_critical_section() will be - * performed in up_sigdeliver(). - */ - - spin_setbit(&g_cpu_irqset, cpu, &g_cpu_irqsetlock, - &g_cpu_irqlock); - /* And make sure that the saved context in the TCB is the same * as the interrupt return context. */ @@ -316,6 +304,23 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) up_savestate(tcb->xcp.regs); } + /* Increment the IRQ lock count so that when the task is restarted, + * it will hold the IRQ spinlock. + */ + + DEBUGASSERT(tcb->irqcount < INT16_MAX); + tcb->irqcount++; + + /* In an SMP configuration, the interrupt disable logic also + * involves spinlocks that are configured per the TCB irqcount + * field. This is logically equivalent to enter_critical_section(). + * The matching call to leave_critical_section() will be + * performed in up_sigdeliver(). + */ + + spin_setbit(&g_cpu_irqset, cpu, &g_cpu_irqsetlock, + &g_cpu_irqlock); + /* RESUME the other CPU if it was PAUSED */ if (cpu != me) @@ -327,7 +332,7 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) /* Otherwise, we are (1) signaling a task is not running from an * interrupt handler or (2) we are not in an interrupt handler and the - * running task is signalling some other non-running task. + * running task is signaling some other non-running task. */ else diff --git a/sched/signal/sig_dispatch.c b/sched/signal/sig_dispatch.c index 600ea4b93b8..67f834a75fa 100644 --- a/sched/signal/sig_dispatch.c +++ b/sched/signal/sig_dispatch.c @@ -413,7 +413,7 @@ int nxsig_tcbdispatch(FAR struct tcb_s *stcb, siginfo_t *info) * Description: * This is the front-end for nxsig_tcbdispatch that should be typically * be used to dispatch a signal. If HAVE_GROUP_MEMBERS is defined, - * then function will follow the group signal delivery algorthrims: + * then function will follow the group signal delivery algorithms: * * This front-end does the following things before calling * nxsig_tcbdispatch.