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nfp: bpf: improve handling for disabled BPF syscall 

I stumbled over a new warning during randconfig testing,
with CONFIG_BPF_SYSCALL disabled:

drivers/net/ethernet/netronome/nfp/nfp_net_offload.c: In function 'nfp_net_bpf_offload':
drivers/net/ethernet/netronome/nfp/nfp_net_offload.c:263:3: error: '*((void *)&res+4)' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/net/ethernet/netronome/nfp/nfp_net_offload.c:263:3: error: 'res.n_instr' may be used uninitialized in this function [-Werror=maybe-uninitialized]

As far as I can tell, this is a false positive caused by the compiler
getting confused about a function that is partially inlined, but it's
easy to avoid while improving the code:

The nfp_bpf_jit() stub helper for that configuration is unusual as it
is defined in a header file but not marked 'static inline'. By moving
the compile-time check into the caller using the IS_ENABLED() macro,
we can remove that stub and simplify the nfp_net_bpf_offload_prepare()
function enough to unconfuse the compiler.

Fixes: 7533fdc0f7 ("nfp: bpf: add hardware bpf offload")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arnd Bergmann 2016-09-23 22:23:59 +02:00 committed by David S. Miller
parent e2072600a2
commit b47c62c5de
2 changed files with 3 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/net/ethernet/netronome/nfp/nfp_bpf.h
View File

@ -192,20 +192,10 @@ struct nfp_bpf_result {
bool dense_mode;
};
#ifdef CONFIG_BPF_SYSCALL
int
nfp_bpf_jit(struct bpf_prog *filter, void *prog, enum nfp_bpf_action_type act,
unsigned int prog_start, unsigned int prog_done,
unsigned int prog_sz, struct nfp_bpf_result *res);
#else
int
nfp_bpf_jit(struct bpf_prog *filter, void *prog, enum nfp_bpf_action_type act,
unsigned int prog_start, unsigned int prog_done,
unsigned int prog_sz, struct nfp_bpf_result *res)
{
return -ENOTSUPP;
}
#endif
int nfp_prog_verify(struct nfp_prog *nfp_prog, struct bpf_prog *prog);

3
drivers/net/ethernet/netronome/nfp/nfp_net_offload.c
View File

@ -148,6 +148,9 @@ nfp_net_bpf_offload_prepare(struct nfp_net *nn,
unsigned int max_mtu;
int ret;
if (!IS_ENABLED(CONFIG_BPF_SYSCALL))
return -ENOTSUPP;
ret = nfp_net_bpf_get_act(nn, cls_bpf);
if (ret < 0)
return ret;