net/iob: Add CONFIG_IOB_OWNER_TRACKING to record IOB owner for debugging

This adds a Kconfig option to optionally track the allocating context
of each IOB (task PID or ISR). The extra metadata makes it much easier
to diagnose IOB leaks, starvation, and ownership/lifetime bugs across
task/ISR boundaries without changing the IOB API seen by callers.

Signed-off-by: Peter van der Perk <peter.vanderperk@nxp.com>

Author: PetervdPerk-NXP

fs/procfs/fs_procfsiobinfo.c

@@ -43,6 +43,7 @@
 #include <nuttx/mm/iob.h>
 #include <nuttx/fs/fs.h>
 #include <nuttx/fs/procfs.h>
+#include <nuttx/spinlock.h>
 
 #include "fs_heap.h"
 
@@ -111,6 +112,11 @@ const struct procfs_operations g_iobinfo_operations =
   iobinfo_stat    /* stat */
 };
 
+#ifdef CONFIG_IOB_OWNER_TRACKING
+extern volatile spinlock_t g_iob_lock;
+extern FAR struct iob_s *g_iob_committed;
+#endif
+
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
@@ -223,6 +229,44 @@ static ssize_t iobinfo_read(FAR struct file *filep, FAR char *buffer,
                              &offset);
   totalsize += copysize;
 
+#ifdef CONFIG_IOB_OWNER_TRACKING
+  buffer   += copysize;
+  buflen   -= copysize;
+
+  irqstate_t flags = spin_lock_irqsave(&g_iob_lock);
+
+  for (unsigned int i = 0; i < CONFIG_IOB_NBUFFERS; i++)
+    {
+      FAR struct iob_s *iob = iob_get_iob_by_index(i);
+
+      /* Print: PID (or -1 for ISR) and flags in hex */
+
+      if (iob->io_owner_flags != 0)
+        {
+          linesize = procfs_snprintf(iobfile->line, IOBINFO_LINELEN,
+                                    "%02d %p -> %p pid=%d flags=0x%02x\n", i,
+                                    iob, iob->io_flink,
+                                    (int)iob->io_owner_pid,
+                                    (unsigned)iob->io_owner_flags);
+        }
+      else
+        {
+          linesize = procfs_snprintf(iobfile->line, IOBINFO_LINELEN,
+                                    "%02d %p -> %p Free\n", i,
+                                    iob, iob->io_flink);
+        }
+
+      copysize = procfs_memcpy(iobfile->line, linesize,
+                               buffer, buflen, &offset);
+      totalsize += copysize;
+
+      buffer   += copysize;
+      buflen   -= copysize;
+    }
+
+  spin_unlock_irqrestore(&g_iob_lock, flags);
+#endif
+
   /* Update the file offset */
 
   filep->f_pos += totalsize;

include/nuttx/mm/iob.h

@@ -126,6 +126,12 @@ struct iob_s
 #endif
   unsigned int io_pktlen; /* Total length of the packet */
 
+ #ifdef CONFIG_IOB_OWNER_TRACKING
+  int16_t           io_owner_pid;
+  uint8_t           io_owner_cpu;   /* CPU index (SMP), 0 on UP */
+  uint8_t           io_owner_flags; /* bit0: ISR; bit1: committed; future use */
+#endif
+
 #ifdef CONFIG_IOB_ALLOC
   iob_free_cb_t io_free;  /* Custom free callback */
   FAR uint8_t  *io_data;
@@ -183,6 +189,10 @@ struct iob_stats_s
 
 void iob_initialize(void);
 
+#ifdef CONFIG_IOB_OWNER_TRACKING
+struct iob_s *iob_get_iob_by_index(unsigned int index);
+#endif
+
 /****************************************************************************
  * Name: iob_timedalloc
  *

mm/iob/Kconfig

@@ -122,5 +122,14 @@ config IOB_DEBUG
 		NOTE that this selection is not available if IOBs are being used
 		to syslog buffering logic (CONFIG_SYSLOG_BUFFER=y)!
 
+config IOB_OWNER_TRACKING
+	bool "Track task/ISR owner of each IOB (for debugging)"
+	default n
+	help
+		When enabled, each IOB carries small metadata indicating the
+		allocating context (task PID or ISR). This helps debug leaks,
+		starvation and ownership bugs without changing the IOB API.
+		Disabled by default to avoid extra RAM on small targets.
+
 endif # MM_IOB
 endmenu # Common I/O buffer support

mm/iob/iob_alloc.c

@@ -38,12 +38,34 @@
 #include <nuttx/nuttx.h>
 #include <nuttx/mm/iob.h>
 
+#ifdef CONFIG_IOB_OWNER_TRACKING
+#include <nuttx/irq.h>         /* up_interrupt_context() */
+#include <nuttx/sched.h>       /* getpid(), this_cpu() if available */
+#endif
+
 #include "iob.h"
 
 /****************************************************************************
  * Private Functions
  ****************************************************************************/
 
+/* Small helper to stamp owner information */
+#ifdef CONFIG_IOB_OWNER_TRACKING
+static inline void iob_set_owner(FAR struct iob_s *iob, bool is_committed)
+{
+  bool isr = up_interrupt_context();
+  int  pid = isr ? -1 : getpid();           /* Kernel-space getpid is OK */
+ #ifdef CONFIG_SMP
+  iob->io_owner_cpu   = (uint8_t)this_cpu(); /* otherwise 0 on UP */
+ #else
+  iob->io_owner_cpu   = 0;
+ #endif
+  iob->io_owner_pid   = (int16_t)pid;
+  iob->io_owner_flags = 0x1 |
+  (isr ? 0x02 : 0x00) | (is_committed ? 0x04 : 0x00);
+}
+#endif
+
 static clock_t iob_allocwait_gettimeout(clock_t start, unsigned int timeout)
 {
   sclock_t tick;
@@ -96,6 +118,9 @@ static FAR struct iob_s *iob_alloc_committed(void)
       iob->io_len    = 0;    /* Length of the data in the entry */
       iob->io_offset = 0;    /* Offset to the beginning of data */
       iob->io_pktlen = 0;    /* Total length of the packet */
+#ifdef CONFIG_IOB_OWNER_TRACKING
+      iob_set_owner(iob, true);
+#endif
     }
 
   spin_unlock_irqrestore(&g_iob_lock, flags);
@@ -135,6 +160,11 @@ static FAR struct iob_s *iob_tryalloc_internal(bool throttled)
           iob->io_len    = 0;    /* Length of the data in the entry */
           iob->io_offset = 0;    /* Offset to the beginning of data */
           iob->io_pktlen = 0;    /* Total length of the packet */
+
+#ifdef CONFIG_IOB_OWNER_TRACKING
+          iob_set_owner(iob, false);
+#endif
+
           return iob;
         }
     }

mm/iob/iob_free.c

@@ -133,6 +133,13 @@ FAR struct iob_s *iob_free(FAR struct iob_s *iob)
           kmm_free(iob);
         }
 
+#ifdef CONFIG_IOB_OWNER_TRACKING
+      /* Clear owner metadata when returning to free list */
+
+      iob->io_owner_pid   = 0;
+      iob->io_owner_cpu   = 0;
+      iob->io_owner_flags = 0;
+#endif
       return next;
     }
 #endif
@@ -196,6 +203,14 @@ FAR struct iob_s *iob_free(FAR struct iob_s *iob)
     }
 #endif
 
+#ifdef CONFIG_IOB_OWNER_TRACKING
+  /* Clear owner metadata when returning to free list */
+
+  iob->io_owner_pid   = 0;
+  iob->io_owner_cpu   = 0;
+  iob->io_owner_flags = 0;
+#endif
+
   /* And return the I/O buffer after the one that was freed */
 
   return next;