| Message ID | 20210609103326.278782-16-toke@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | Clean up and document RCU-based object protection for XDP_REDIRECT | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | fail | Series longer than 15 patches |
| netdev/tree_selection | success | Clearly marked for bpf-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 10 maintainers not CCed: yhs@fb.com kpsingh@kernel.org daniel@iogearbox.net andrii@kernel.org hawk@kernel.org ast@kernel.org john.fastabend@gmail.com songliubraving@fb.com davem@davemloft.net kuba@kernel.org |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 15 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
On Wed, 9 Jun 2021 at 13:33, Toke Høiland-Jørgensen <toke@redhat.com> wrote: > > The netsec driver has a rcu_read_lock()/rcu_read_unlock() pair around the > full RX loop, covering everything up to and including xdp_do_flush(). This > is actually the correct behaviour, but because it all happens in a single > NAPI poll cycle (and thus under local_bh_disable()), it is also technically > redundant. > > With the addition of RCU annotations to the XDP_REDIRECT map types that > take bh execution into account, lockdep even understands this to be safe, > so there's really no reason to keep the rcu_read_lock() around anymore, so > let's just remove it. > > Cc: Jassi Brar <jaswinder.singh@linaro.org> > Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org> > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> > --- > drivers/net/ethernet/socionext/netsec.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c > index dfc85cc68173..20d148c019d8 100644 > --- a/drivers/net/ethernet/socionext/netsec.c > +++ b/drivers/net/ethernet/socionext/netsec.c > @@ -958,7 +958,6 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) > > xdp_init_buff(&xdp, PAGE_SIZE, &dring->xdp_rxq); > > - rcu_read_lock(); > xdp_prog = READ_ONCE(priv->xdp_prog); > dma_dir = page_pool_get_dma_dir(dring->page_pool); > > @@ -1069,8 +1068,6 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) > } > netsec_finalize_xdp_rx(priv, xdp_act, xdp_xmit); > > - rcu_read_unlock(); > - > return done; > } > > -- > 2.31.1 > Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c index dfc85cc68173..20d148c019d8 100644 --- a/drivers/net/ethernet/socionext/netsec.c +++ b/drivers/net/ethernet/socionext/netsec.c @@ -958,7 +958,6 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) xdp_init_buff(&xdp, PAGE_SIZE, &dring->xdp_rxq); - rcu_read_lock(); xdp_prog = READ_ONCE(priv->xdp_prog); dma_dir = page_pool_get_dma_dir(dring->page_pool); @@ -1069,8 +1068,6 @@ static int netsec_process_rx(struct netsec_priv *priv, int budget) } netsec_finalize_xdp_rx(priv, xdp_act, xdp_xmit); - rcu_read_unlock(); - return done; }
The netsec driver has a rcu_read_lock()/rcu_read_unlock() pair around the full RX loop, covering everything up to and including xdp_do_flush(). This is actually the correct behaviour, but because it all happens in a single NAPI poll cycle (and thus under local_bh_disable()), it is also technically redundant. With the addition of RCU annotations to the XDP_REDIRECT map types that take bh execution into account, lockdep even understands this to be safe, so there's really no reason to keep the rcu_read_lock() around anymore, so let's just remove it. Cc: Jassi Brar <jaswinder.singh@linaro.org> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> --- drivers/net/ethernet/socionext/netsec.c | 3 --- 1 file changed, 3 deletions(-)