| Message ID | 20200114231949.20106-1-fw@strlen.de |
|---|---|
| State | Accepted, archived |
| Delegated to: | Matthieu Baerts |
| Headers | show |
| Series | subflow: remove unneded memory barriers | expand |
On Wed, 15 Jan 2020, Florian Westphal wrote: > squashto: mptcp: Implement MPTCP receive path > > The bit set operation has no prior dependencies, so > smp_mb__before_atomic() is not needed. > > It has no followup depenency: the woken task will always see the > bit set, plus wakeup code (called via sk_data_ready) acquires a spinlock. > > Signed-off-by: Florian Westphal <fw@strlen.de> > --- > net/mptcp/subflow.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c > index abd97d1a8645..ae9173040f17 100644 > --- a/net/mptcp/subflow.c > +++ b/net/mptcp/subflow.c > @@ -712,9 +712,7 @@ static void subflow_data_ready(struct sock *sk) > } > > if (mptcp_subflow_data_available(sk)) { > - smp_mb__before_atomic(); > set_bit(MPTCP_DATA_READY, &mptcp_sk(parent)->flags); > - smp_mb__after_atomic(); > > parent->sk_data_ready(parent); > } > @@ -869,9 +867,7 @@ static void subflow_state_change(struct sock *sk) > * the data available machinery here. > */ > if (parent && subflow->mp_capable && mptcp_subflow_data_available(sk)) { > - smp_mb__before_atomic(); > set_bit(MPTCP_DATA_READY, &mptcp_sk(parent)->flags); > - smp_mb__after_atomic(); > > parent->sk_data_ready(parent); > } > -- > 2.24.1 I agree that these barriers are not needed. -- Mat Martineau Intel
Hi Florian, Mat, On 15/01/2020 02:34, Mat Martineau wrote: > On Wed, 15 Jan 2020, Florian Westphal wrote: > >> squashto: mptcp: Implement MPTCP receive path >> >> The bit set operation has no prior dependencies, so >> smp_mb__before_atomic() is not needed. >> >> It has no followup depenency: the woken task will always see the >> bit set, plus wakeup code (called via sk_data_ready) acquires a spinlock. [...] > I agree that these barriers are not needed. Thank you for the patch and the review! - 53f6baf4672c: "squashed" in "mptcp: Implement MPTCP receive path" - 41b3253570a8..91800c0574b2: result Tests + export will be launched soon! Cheers, Matt
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index abd97d1a8645..ae9173040f17 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -712,9 +712,7 @@ static void subflow_data_ready(struct sock *sk) } if (mptcp_subflow_data_available(sk)) { - smp_mb__before_atomic(); set_bit(MPTCP_DATA_READY, &mptcp_sk(parent)->flags); - smp_mb__after_atomic(); parent->sk_data_ready(parent); } @@ -869,9 +867,7 @@ static void subflow_state_change(struct sock *sk) * the data available machinery here. */ if (parent && subflow->mp_capable && mptcp_subflow_data_available(sk)) { - smp_mb__before_atomic(); set_bit(MPTCP_DATA_READY, &mptcp_sk(parent)->flags); - smp_mb__after_atomic(); parent->sk_data_ready(parent); }
squashto: mptcp: Implement MPTCP receive path The bit set operation has no prior dependencies, so smp_mb__before_atomic() is not needed. It has no followup depenency: the woken task will always see the bit set, plus wakeup code (called via sk_data_ready) acquires a spinlock. Signed-off-by: Florian Westphal <fw@strlen.de> --- net/mptcp/subflow.c | 4 ---- 1 file changed, 4 deletions(-)