From: Karel Zak <kzak@redhat.com>
Date: Thu, 16 Oct 2008 21:37:38 +0000 (+0200)
Subject: hwclock: remove "cli" and "sti" from i386 CMOS code
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1a55ee51ccdd09897985200a3ea56c35be29eb21;p=util-linux

hwclock: remove "cli" and "sti" from i386 CMOS code

The protection against context switch is nonsense. There is possible
to optimize the access to CMOS by mlockall(MCL_CURRENT) and SCHED_FIFO.

For more details see: http://lkml.org/lkml/2008/10/12/132

Reported-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/hwclock/cmos.c b/hwclock/cmos.c
index ca3ca61e..91b358d2 100644
--- a/hwclock/cmos.c
+++ b/hwclock/cmos.c
@@ -216,30 +216,7 @@ set_cmos_access(int Jensen, int funky_toy) {
 #endif
 
 
-
-
-#ifdef __i386__
-
-/*
- * Try to do CMOS access atomically, so that no other processes
- * can get a time slice while we are reading or setting the clock.
- * (Also, if the kernel time is synchronized with an external source,
- *  the kernel itself will fiddle with the RTC every 11 minutes.)
- */
-
-static unsigned long
-atomic(const char *name, unsigned long (*op)(unsigned long),
-       unsigned long arg)
-{
-  unsigned long v;
-  __asm__ volatile ("cli");
-  v = (*op)(arg);
-  __asm__ volatile ("sti");
-  return v;
-}
-
-#elif __alpha__
-
+#if __alpha__
 /*
  * The Alpha doesn't allow user-level code to disable interrupts (for
  * good reasons).  Instead, we ensure atomic operation by performing
@@ -267,12 +244,14 @@ atomic(const char *name, unsigned long (*op)(unsigned long),
   fprintf(stderr, _("%s: atomic %s failed for 1000 iterations!"), progname, name);
   exit(1);
 }
-
 #else
 
 /*
  * Hmmh, this isn't very atomic.  Maybe we should force an error
  * instead?
+ *
+ * TODO: optimize the access to CMOS by mlockall(MCL_CURRENT)
+ *       and SCHED_FIFO
  */
 static unsigned long
 atomic(const char *name, unsigned long (*op)(unsigned long),