Messages in this thread | | | From | Jeff Moyer <> | Date | Mon, 13 Feb 2006 18:00:10 -0500 | Subject | Re: [patch] fix BUG: in fw_realloc_buffer |
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==> Regarding Re: [patch] fix BUG: in fw_realloc_buffer; Andrew Morton <akpm@osdl.org> adds:
akpm> Jeff Moyer <jmoyer@redhat.com> wrote: >> >> Hi, >> >> The fw_realloc_buffer routine does not handle an increase in buffer size of >> more than 4k. It's not clear to me why it expects that it will only get an >> extra 4k of data. The attached patch modifies fw_realloc_buffer to vmalloc >> as much memory as is requested, instead of what we previously had + 4k. >> >> I've tested this on my laptop, which would crash occaisionally on boot >> without the patch. With the patch, it hasn't crashed, but I can't be >> certain that this code path is exercised. >> >> Comments are very welcome. >> [snip]
akpm> A little bit neater this way, I think?
> --- devel/drivers/base/firmware_class.c~firmware-fix-bug-in-fw_realloc_buffer 2006-02-13 14:45:52.000000000 -0800 > +++ devel-akpm/drivers/base/firmware_class.c 2006-02-13 14:52:05.000000000 -0800 > @@ -211,18 +211,20 @@ static int > fw_realloc_buffer(struct firmware_priv *fw_priv, int min_size) > { > u8 *new_data; > + int new_size = fw_priv->alloc_size;
> if (min_size <= fw_priv->alloc_size) > return 0;
> - new_data = vmalloc(fw_priv->alloc_size + PAGE_SIZE); > + new_size = ALIGN(min_size, PAGE_SIZE); > + new_data = vmalloc(new_size); > if (!new_data) { > printk(KERN_ERR "%s: unable to alloc buffer\n", __FUNCTION__); > /* Make sure that we don't keep incomplete data */ > fw_load_abort(fw_priv); > return -ENOMEM; > } > - fw_priv->alloc_size += PAGE_SIZE; > + fw_priv->alloc_size = new_size; > if (fw_priv->fw->data) { > memcpy(new_data, fw_priv->fw->data, fw_priv->fw->size); > vfree(fw_priv->fw->data); > _
Well, I wasn't sure that you would only need to increase by a PAGE. If you only need to account for page_size + alignment, then yes, this is better. It simply wasn't clear to me that this is how we are called. If I'm not mistaken, this is the write routine for a file in sysfs. If that is the case, why should we assume that writes are broken up into PAGE_SIZE chunks?
Thanks,
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