Re: [PATCH] fix stack usage in fs/intermezzo/journal.c

["Randy.Dunlap" <rddunlap@osdl.org>]

On Fri, 14 Mar 2003 16:53:52 +0100 Joern Engel <joern@wohnheim.fh-wedel.de> wrote:

| Hi!
| 
| This moves two 4k buffers from stack to heap. Compiles, untested, but
| looks trivial.
| -- 
| 
| --- linux-2.5.64/fs/intermezzo/journal.c	Mon Feb 24 20:05:05 2003
| +++ linux-2.5.64-i2o/fs/intermezzo/journal.c	Thu Mar 13 13:14:12 2003
| @@ -1245,6 +1245,7 @@
|          struct file *f;
|          int len;
|          loff_t read_off, write_off, bytes;
| +        char *buf;
|  
|          ENTRY;
|  
| @@ -1255,15 +1256,18 @@
|                  return f;
|          }
|  
| +        buf = kmalloc(4096, GFP_KERNEL);
| +        if (!buf)
| +                return ERR_PTR(-ENOMEM);
| +
|          write_off = 0;
|          read_off = start;
|          bytes = fset->fset_kml.fd_offset - start;
|          while (bytes > 0) {
| -                char buf[4096];
|                  int toread;
|  
| -                if (bytes > sizeof(buf))
| -                        toread = sizeof(buf);
| +                if (bytes > sizeof(*buf))
| +                        toread = sizeof(*buf);

I guess one of us needs some guidance here.
I thought that sizeof(*buf) == 1 here, not 4096.  Anybody?
I don't see how sizeof() can determine the kmalloc-ed size,
so I would use BUF_SIZE instead, with
#define BUF_SIZE	4096


Same for <record> below (snipped).

--
~Randy