(nuttx) branch master updated: armv8-m: skip scheduler bookkeeping without task switch

[jiuzhudong]

This is an automated email from the ASF dual-hosted git repository.

Donny9 pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/nuttx.git


The following commit(s) were added to refs/heads/master by this push:
     new ace658fb2bc armv8-m: skip scheduler bookkeeping without task switch
ace658fb2bc is described below

commit ace658fb2bcf51152cd55e1e5bc44399f659fec1
Author: chao an <anchao.arc...@bytedance.com>
AuthorDate: Tue Oct 20 16:20:27 2026 +0800

    armv8-m: skip scheduler bookkeeping without task switch
    
    The ARMv8-M IRQ path can return to the interrupted task without
    performing a context switch.  In that case, calling
    nxsched_switch_context() still runs scheduler switch bookkeeping even
    though no task changed.
    
    Guard the scheduler bookkeeping with a running-task comparison, but
    keep reloading tcb->xcp.regs unconditionally.  The unconditional reload
    preserves cases such as signal delivery where the return register
    context may be updated without switching tasks.
    
    Signed-off-by: chao an <anchao.arc...@bytedance.com>
---
 arch/arm/src/armv8-m/arm_doirq.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/arch/arm/src/armv8-m/arm_doirq.c b/arch/arm/src/armv8-m/arm_doirq.c
index 22c011e3fa5..8f2206aae1b 100644
--- a/arch/arm/src/armv8-m/arm_doirq.c
+++ b/arch/arm/src/armv8-m/arm_doirq.c
@@ -115,20 +115,24 @@ uint32_t *arm_doirq(int irq, uint32_t *regs)
     }
 #endif
 
-  /* Update scheduler parameters.
-   * The arm-m architecture svc call will trigger an interrupt,
-   * and the actual context switch is executed after doirq is completed,
-   * so only the scheduling information needs to be updated in doirq.
-   */
+  if (*running_task != tcb)
+    {
+      /* Update scheduler parameters.
+       * The arm-m architecture svc call will trigger an interrupt,
+       * and the actual context switch is executed after doirq is completed,
+       * so only the scheduling information needs to be updated in doirq.
+       */
 
-  nxsched_switch_context(*running_task, tcb);
+      nxsched_switch_context(*running_task, tcb);
 
-  /* Record the new "running" task when context switch occurred.
-   * g_running_tasks[] is only used by assertion logic for reporting
-   * crashes.
-   */
+      /* Record the new "running" task when context switch occurred.
+       * g_running_tasks[] is only used by assertion logic for reporting
+       * crashes.
+       */
+
+      *running_task = tcb;
+    }
 
-  *running_task = tcb;
   regs = tcb->xcp.regs;
 #endif