bk commit into 4.1 tree (Kristofer.Pettersson:1.2588) BUG#24751

[kpettersson]

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ChangeSet@stripped, 2007-01-10 18:04:01+01:00, Kristofer.Pettersson@naruto. +1 -0
  Bug#24751 - Possible infinit loop in init_io_cache() when insufficient memory
  - When cache memory can't be allocated size is recaclulated using 3/4 of
    the requested memory. This number is rounded to the nearest min_cache
    step. However with the previous implementation the new cache size might
    become bigger than requested because of round errors and thus we get
    an infinit loop.
  - This patch fixes this problem by ensuring that the rounded number
    always will be smaller.

  mysys/mf_iocache.c@stripped, 2007-01-10 18:01:42+01:00, Kristofer.Pettersson@naruto. +1 -1
    - Added mask to cachesize to ensure that new cache size is smaller than
      current.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	Kristofer.Pettersson
# Host:	naruto.
# Root:	C:/cpp/bug24751/my41-bug24751

--- 1.51/mysys/mf_iocache.c	2007-01-10 18:04:13 +01:00
+++ 1.52/mysys/mf_iocache.c	2007-01-10 18:04:13 +01:00
@@ -222,7 +222,7 @@ int init_io_cache(IO_CACHE *info, File f
       }
       if (cachesize == min_cache)
 	DBUG_RETURN(2);				/* Can't alloc cache */
-      cachesize= (uint) ((long) cachesize*3/4); /* Try with less memory */
+      cachesize= (uint) ((long) cachesize*3/4 & (ulong)~(min_cache-1)); /* Try with
less memory */
     }
   }