[PATCH] threads: Update PID limit comment according to futex UAPI change

[Jann Horn]

The futex UAPI changed back in commit 76b81e2b0e22 ("[PATCH] lightweight
robust futexes updates 2"), which landed in v2.6.17: FUTEX_TID_MASK is now
0x3fffffff instead of 0x1fffffff. Update the corresponding comment in
include/linux/threads.h.

Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
---
 include/linux/threads.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/threads.h b/include/linux/threads.h
index 3086dba525e20..18d5a74bcc3dd 100644
--- a/include/linux/threads.h
+++ b/include/linux/threads.h
@@ -29,7 +29,7 @@
 
 /*
  * A maximum of 4 million PIDs should be enough for a while.
- * [NOTE: PID/TIDs are limited to 2^29 ~= 500+ million, see futex.h.]
+ * [NOTE: PID/TIDs are limited to 2^30 ~= 1 billion, see FUTEX_TID_MASK.]
  */
 #define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
 	(sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
-- 
2.25.0.265.gbab2e86ba0-goog