svn commit: r213714 - in head/sys: kern sys

[David Xu]

Author: davidxu
Date: Tue Oct 12 00:36:56 2010
New Revision: 213714
URL: http://svn.freebsd.org/changeset/base/213714

Log:
  Add a flag TDF_TIDHASH to prevent a thread from being
  added to or removed from thread hash table multiple times.

Modified:
  head/sys/kern/kern_thread.c
  head/sys/sys/proc.h

Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c Mon Oct 11 23:24:57 2010        (r213713)
+++ head/sys/kern/kern_thread.c Tue Oct 12 00:36:56 2010        (r213714)
@@ -981,7 +981,12 @@ void
 tidhash_add(struct thread *td)
 {
        rw_wlock(&tidhash_lock);
-       LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
+       thread_lock(td);
+       if ((td->td_flags & TDF_TIDHASH) == 0) {
+               LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
+               td->td_flags |= TDF_TIDHASH;
+       }
+       thread_unlock(td);
        rw_wunlock(&tidhash_lock);
 }
 
@@ -989,6 +994,11 @@ void
 tidhash_remove(struct thread *td)
 {
        rw_wlock(&tidhash_lock);
-       LIST_REMOVE(td, td_hash);
+       thread_lock(td);
+       if ((td->td_flags & TDF_TIDHASH) != 0) {
+               LIST_REMOVE(td, td_hash);
+               td->td_flags &= ~TDF_TIDHASH;
+       }
+       thread_unlock(td);
        rw_wunlock(&tidhash_lock);
 }

Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Mon Oct 11 23:24:57 2010        (r213713)
+++ head/sys/sys/proc.h Tue Oct 12 00:36:56 2010        (r213714)
@@ -353,7 +353,7 @@ do {                                                        
                \
 #define        TDF_NEEDRESCHED 0x00010000 /* Thread needs to yield. */
 #define        TDF_NEEDSIGCHK  0x00020000 /* Thread may need signal delivery. 
*/
 #define        TDF_NOLOAD      0x00040000 /* Ignore during load avg 
calculations. */
-#define        TDF_UNUSED19    0x00080000 /* Thread is sleeping on a umtx. */
+#define        TDF_TIDHASH     0x00080000 /* Thread is on hash table. */
 #define        TDF_THRWAKEUP   0x00100000 /* Libthr thread must not suspend 
itself. */
 #define        TDF_UNUSED21    0x00200000 /* --available-- */
 #define        TDF_SWAPINREQ   0x00400000 /* Swapin request due to wakeup. */
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