From: Ben Gras <ben@minix3.org>
Date: Tue, 1 Dec 2009 16:46:27 +0000 (+0000)
Subject: fix for race condition - IRQ can happen between clearing the endpoint
X-Git-Tag: v3.1.6~185
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/Bv9ARM.html?a=commitdiff_plain;h=7c0cdc61bc348e0a93c2c50a2a9341d9554619fb;p=minix.git

fix for race condition - IRQ can happen between clearing the endpoint
of the handling process and before removing the hook. The handler function
will panic then.
---

diff --git a/kernel/system/do_exit.c b/kernel/system/do_exit.c
index 05200601b..d5f85fbed 100644
--- a/kernel/system/do_exit.c
+++ b/kernel/system/do_exit.c
@@ -56,6 +56,14 @@ register struct proc *rc;		/* slot of process to clean up */
   /* Don't clear if already cleared. */
   if(isemptyp(rc)) return;
 
+  /* Check the table with IRQ hooks to see if hooks should be released. */
+  for (i=0; i < NR_IRQ_HOOKS; i++) {
+      int proc;
+      if (rc->p_endpoint == irq_hooks[i].proc_nr_e) {
+        rm_irq_handler(&irq_hooks[i]);	/* remove interrupt handler */
+        irq_hooks[i].proc_nr_e = NONE;	/* mark hook as free */
+      } 
+  }
 
   /* Remove the process' ability to send and receive messages */
   clear_endpoint(rc);
@@ -69,15 +77,6 @@ register struct proc *rc;		/* slot of process to clean up */
    */
   RTS_LOCK_SETFLAGS(rc, RTS_SLOT_FREE);
 
-  /* Check the table with IRQ hooks to see if hooks should be released. */
-  for (i=0; i < NR_IRQ_HOOKS; i++) {
-      int proc;
-      if (rc->p_endpoint == irq_hooks[i].proc_nr_e) {
-        rm_irq_handler(&irq_hooks[i]);	/* remove interrupt handler */
-        irq_hooks[i].proc_nr_e = NONE;	/* mark hook as free */
-      } 
-  }
-
   /* Release the process table slot. If this is a system process, also
    * release its privilege structure.  Further cleanup is not needed at
    * this point. All important fields are reinitialized when the