sched/signal: reclaim dynamic sigactions

This adds support of pre- and dynamic allocations of sigactions. Current never-return behavior can be acheived by setting SIG_ALLOC_ACTIONS to a number larger than 1. Signed-off-by: Yanfeng Liu <[email protected]>
yf13 · Jun 18, 2024 · 0be97b4 · 0be97b4
1 parent c885ba7
commit 0be97b4
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Showing 4 changed files with 51 additions and 8 deletions.
diff --git a/sched/Kconfig b/sched/Kconfig
@@ -1548,6 +1548,20 @@ endmenu # RTOS hooks
 
 menu "Signal Configuration"
 
+config SIG_PREALLOC_ACTIONS
+	int "Number of pre-allocated sigactions"
+	default 4
+	---help---
+		The number of pre-allocated sigaction structures.
+
+config SIG_ALLOC_ACTIONS
+	int "Num of sigactions to allocate per time"
+	default 1
+	---help---
+		The number of sigactions to allocate per time. Note that
+		if this number is larger than 1, the allocation won't be
+		returned to the heap but kept in a free list for reuse.
+
 config SIG_PREALLOC_IRQ_ACTIONS
 	int "Number of pre-allocated irq actions"
 	default 4 if DEFAULT_SMALL

diff --git a/sched/signal/sig_action.c b/sched/signal/sig_action.c
@@ -67,12 +67,12 @@ static void nxsig_alloc_actionblock(void)
 
   /* Allocate a block of signal actions */
 
-  sigact = kmm_malloc((sizeof(sigactq_t)) * NUM_SIGNAL_ACTIONS);
+  sigact = kmm_malloc((sizeof(sigactq_t)) * CONFIG_SIG_ALLOC_ACTIONS);
   if (sigact != NULL)
     {
       flags = spin_lock_irqsave(&g_sigaction_spin);
 
-      for (i = 0; i < NUM_SIGNAL_ACTIONS; i++)
+      for (i = 0; i < CONFIG_SIG_ALLOC_ACTIONS; i++)
         {
           sq_addlast((FAR sq_entry_t *)sigact++, &g_sigfreeaction);
         }
@@ -100,7 +100,7 @@ static FAR sigactq_t *nxsig_alloc_action(void)
   sigact = (FAR sigactq_t *)sq_remfirst(&g_sigfreeaction);
   spin_unlock_irqrestore(&g_sigaction_spin, flags);
 
-  /* Check if we got one. */
+  /* Check if we got one via loop as not in critical section now */
 
   while (!sigact)
     {
@@ -409,9 +409,16 @@ void nxsig_release_action(FAR sigactq_t *sigact)
 {
   irqstate_t flags;
 
-  /* Just put it back on the free list */
+  if (CONFIG_SIG_ALLOC_ACTIONS > 1 || IS_PREALLOC_ACTION(sigact))
+    {
+      /* Non-preallocated instances will never return to heap! */
 
-  flags = spin_lock_irqsave(&g_sigaction_spin);
-  sq_addlast((FAR sq_entry_t *)sigact, &g_sigfreeaction);
-  spin_unlock_irqrestore(&g_sigaction_spin, flags);
+      flags = spin_lock_irqsave(&g_sigaction_spin);
+      sq_addlast((FAR sq_entry_t *)sigact, &g_sigfreeaction);
+      spin_unlock_irqrestore(&g_sigaction_spin, flags);
+    }
+  else
+    {
+      kmm_free(sigact);
+    }
 }
diff --git a/sched/signal/sig_initialize.c b/sched/signal/sig_initialize.c
@@ -55,6 +55,10 @@ struct sigpool_s
 
 sq_queue_t  g_sigfreeaction;
 
+#if CONFIG_SIG_PREALLOC_ACTIONS > 0
+sigactq_t   g_sigactions[CONFIG_SIG_PREALLOC_ACTIONS];
+#endif
+
 /* The g_sigpendingaction data structure is a list of available pending
  * signal action structures.
  */
@@ -155,6 +159,9 @@ static void *nxsig_init_pendingsignalblock(FAR sq_queue_t *siglist,
 void nxsig_initialize(void)
 {
   FAR void *sigpool = &g_sigpool;
+#if CONFIG_SIG_PREALLOC_ACTIONS > 0
+  int i;
+#endif
 
   sched_trace_begin();
 
@@ -166,6 +173,13 @@ void nxsig_initialize(void)
   sq_init(&g_sigpendingsignal);
   sq_init(&g_sigpendingirqsignal);
 
+#if CONFIG_SIG_PREALLOC_ACTIONS > 0
+  for (i = 0; i < CONFIG_SIG_PREALLOC_ACTIONS; i++)
+    {
+      sq_addlast((FAR sq_entry_t *)(g_sigactions + i), &g_sigfreeaction);
+    }
+#endif
+
   sigpool = nxsig_init_block(&g_sigpendingaction, sigpool,
                              NUM_PENDING_ACTIONS, SIG_ALLOC_FIXED);
   sigpool = nxsig_init_block(&g_sigpendingirqaction, sigpool,

diff --git a/sched/signal/signal.h b/sched/signal/signal.h
@@ -42,7 +42,6 @@
  * allocate in a block
  */
 
-#define NUM_SIGNAL_ACTIONS       4
 #define NUM_PENDING_ACTIONS      4
 #define NUM_SIGNALS_PENDING      4
 
@@ -111,6 +110,15 @@ typedef struct sigq_s sigq_t;
 
 extern sq_queue_t  g_sigfreeaction;
 
+#if CONFIG_SIG_PREALLOC_ACTIONS > 0
+extern sigactq_t   g_sigactions[CONFIG_SIG_PREALLOC_ACTIONS];
+#define IS_PREALLOC_ACTION(x) ( \
+          (uintptr_t)(x) >= (uintptr_t)&g_sigactions && \
+          (uintptr_t)(x) < ((uintptr_t)&g_sigactions) + sizeof(g_sigactions))
+#else
+#define IS_PREALLOC_ACTION(x) false
+#endif
+
 /* The g_sigpendingaction data structure is a list of available pending
  * signal action structures.
  */