Messages in this thread | | | From | (Eric W. Biederman) | Date | Mon, 13 Dec 2010 13:35:25 -0800 | Subject | Re: [PATCH] netlink: fix gcc -Wconversion compilation warning |
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"Kirill A. Shutsemov" <kirill@shutemov.name> writes:
> From: Dmitry V. Levin <ldv@altlinux.org> > > $ cat << EOF | gcc -Wconversion -xc -S -o/dev/null - > unsigned f(void) {return NLMSG_HDRLEN;} > EOF > <stdin>: In function 'f': > <stdin>:3:26: warning: negative integer implicitly converted to unsigned type > This doesn't look like a bad fix, but I believe things will fail if we give NLMSG_ALIGN an unsigned long like size_t. Say like sizeof.
Admittedly it has to be a huge size but still if we are going to go fixing things...
And then there is the silliness that NLMSG_HDRLEN forces itself to be an int, when it start out as a size_t.
So I think NLMSG_ALIGN either needs to operation exclusively on unsigned longs aka size_t, or it needs to be type preserving.
Do you have time to look at this a bit more?
> Signed-off-by: Dmitry V. Levin <ldv@altlinux.org> > Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> > --- > include/linux/netlink.h | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/include/linux/netlink.h b/include/linux/netlink.h > index 1235669..e2b9e63 100644 > --- a/include/linux/netlink.h > +++ b/include/linux/netlink.h > @@ -70,7 +70,7 @@ struct nlmsghdr { > Check NLM_F_EXCL > */ > > -#define NLMSG_ALIGNTO 4 > +#define NLMSG_ALIGNTO 4U > #define NLMSG_ALIGN(len) ( ((len)+NLMSG_ALIGNTO-1) & ~(NLMSG_ALIGNTO-1) ) > #define NLMSG_HDRLEN ((int) NLMSG_ALIGN(sizeof(struct nlmsghdr))) > #define NLMSG_LENGTH(len) ((len)+NLMSG_ALIGN(NLMSG_HDRLEN))
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