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Xtensa SMP: Avoid a nasty situation in SMP by assuring that up_release_pending() is not re-entered.

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This commit is contained in:
Gregory Nutt
2016-12-21 09:07:54 -06:00
parent c1e2606526
commit 733a57b4df
2 changed files with 83 additions and 56 deletions
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arch/xtensa/src/common/xtensa_cpupause.c
+6
View File
@@ -229,6 +229,9 @@ int up_cpu_pause(int cpu)
* handler from returning until up_cpu_resume() is called; g_cpu_paused
* is a handshake that will prefent this function from returning until
* the CPU is actually paused.
*
* REVISIT: OR should there be logic to just skip this if the other CPU
* is already paused.
*/
DEBUGASSERT(!spin_islocked(&g_cpu_wait[cpu]) &&
@@ -297,6 +300,9 @@ int up_cpu_resume(int cpu)
/* Release the spinlock. Releasing the spinlock will cause the SGI2
* handler on 'cpu' to continue and return from interrupt to the newly
* established thread.
*
* REVISIT: Should there be a more positive handshake to assure that the
* resumption is complete before returning.
*/
DEBUGASSERT(spin_islocked(&g_cpu_wait[cpu]) &&
arch/xtensa/src/common/xtensa_releasepending.c
+77 -56
View File
@@ -39,6 +39,7 @@
#include <nuttx/config.h>
#include <stdbool.h>
#include <sched.h>
#include <debug.h>
@@ -68,92 +69,112 @@
void up_release_pending(void)
{
struct tcb_s *rtcb = this_task();
#ifdef CONFIG_SMP
static bool busy = false;
#endif
sinfo("From TCB=%p\n", rtcb);
/* Merge the g_pendingtasks list into the ready-to-run task list */
/* In SMP configurations, this function will be called as part of leaving
* the critical section. In that case, it may be re-entered as part of
* the sched_addreadytorun() processing. We have to guard against that
* case.
*/
/* sched_lock(); */
if (sched_mergepending())
#ifdef CONFIG_SMP
if (!busy)
{
/* The currently active task has changed! We will need to
* switch contexts.
*/
busy = true;
#endif
/* Update scheduler parameters */
/* Merge the g_pendingtasks list into the ready-to-run task list */
sched_suspend_scheduler(rtcb);
/* Are we operating in interrupt context? */
if (CURRENT_REGS)
/* sched_lock(); */
if (sched_mergepending())
{
/* Yes, then we have to do things differently.
* Just copy the CURRENT_REGS into the OLD rtcb.
/* The currently active task has changed! We will need to
* switch contexts.
*/
xtensa_savestate(rtcb->xcp.regs);
/* Restore the exception context of the rtcb at the (new) head
* of the ready-to-run task list.
*/
rtcb = this_task();
/* Update scheduler parameters */
sched_resume_scheduler(rtcb);
sched_suspend_scheduler(rtcb);
/* Then switch contexts. Any necessary address environment
* changes will be made when the interrupt returns.
/* Are we operating in interrupt context? */
if (CURRENT_REGS)
{
/* Yes, then we have to do things differently.
* Just copy the CURRENT_REGS into the OLD rtcb.
*/
xtensa_savestate(rtcb->xcp.regs);
/* Restore the exception context of the rtcb at the (new) head
* of the ready-to-run task list.
*/
rtcb = this_task();
/* Update scheduler parameters */
sched_resume_scheduler(rtcb);
/* Then switch contexts. Any necessary address environment
* changes will be made when the interrupt returns.
*/
xtensa_restorestate(rtcb->xcp.regs);
}
/* Copy the exception context into the TCB of the task that
* was currently active. if up_saveusercontext returns a non-zero
* value, then this is really the previously running task
* restarting!
*/
xtensa_restorestate(rtcb->xcp.regs);
}
/* Copy the exception context into the TCB of the task that
* was currently active. if up_saveusercontext returns a non-zero
* value, then this is really the previously running task
* restarting!
*/
else if (!xtensa_context_save(rtcb->xcp.regs))
{
else if (!xtensa_context_save(rtcb->xcp.regs))
{
#if XCHAL_CP_NUM > 0
/* Save the co-processor state in in the suspended thread's co-
* processor save area.
*/
/* Save the co-processor state in in the suspended thread's co-
* processor save area.
*/
xtensa_coproc_savestate(&rtcb->xcp.cpstate);
xtensa_coproc_savestate(&rtcb->xcp.cpstate);
#endif
/* Restore the exception context of the rtcb at the (new) head
* of the ready-to-run task list.
*/
/* Restore the exception context of the rtcb at the (new) head
* of the ready-to-run task list.
*/
rtcb = this_task();
rtcb = this_task();
#if XCHAL_CP_NUM > 0
/* Set up the co-processor state for the newly started thread. */
/* Set up the co-processor state for the newly started thread. */
xtensa_coproc_restorestate(&rtcb->xcp.cpstate);
xtensa_coproc_restorestate(&rtcb->xcp.cpstate);
#endif
#ifdef CONFIG_ARCH_ADDRENV
/* Make sure that the address environment for the previously
* running task is closed down gracefully (data caches dump,
* MMU flushed) and set up the address environment for the new
* thread at the head of the ready-to-run list.
*/
/* Make sure that the address environment for the previously
* running task is closed down gracefully (data caches dump,
* MMU flushed) and set up the address environment for the new
* thread at the head of the ready-to-run list.
*/
(void)group_addrenv(rtcb);
(void)group_addrenv(rtcb);
#endif
/* Update scheduler parameters */
/* Update scheduler parameters */
sched_resume_scheduler(rtcb);
sched_resume_scheduler(rtcb);
/* Then switch contexts */
/* Then switch contexts */
xtensa_context_restore(rtcb->xcp.regs);
xtensa_context_restore(rtcb->xcp.regs);
}
}
#ifdef CONFIG_SMP
busy = false;
}
#endif
}