| Message ID | 20190906111807.14978-1-bmt@zurich.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | RDMA/siw: Relax from kmap_atomic() use in TX path | expand |
Hey Bernard, is the code below called directly from the driver’s post_send function? If so it must use atomic...I think. Stevo > On Sep 6, 2019, at 6:18 AM, Bernard Metzler <bmt@zurich.ibm.com> wrote: > > Since the transmit path is never executed in an atomic > context, we do not need kmap_atomic() and can always > use less demanding kmap(). > > Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com> > --- > drivers/infiniband/sw/siw/siw_qp_tx.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) > > diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c > index 8e72f955921d..5d97bba0ce6d 100644 > --- a/drivers/infiniband/sw/siw/siw_qp_tx.c > +++ b/drivers/infiniband/sw/siw/siw_qp_tx.c > @@ -76,16 +76,15 @@ static int siw_try_1seg(struct siw_iwarp_tx *c_tx, void *paddr) > if (unlikely(!p)) > return -EFAULT; > > - buffer = kmap_atomic(p); > + buffer = kmap(p); > > if (likely(PAGE_SIZE - off >= bytes)) { > memcpy(paddr, buffer + off, bytes); > - kunmap_atomic(buffer); > } else { > unsigned long part = bytes - (PAGE_SIZE - off); > > memcpy(paddr, buffer + off, part); > - kunmap_atomic(buffer); > + kunmap(p); > > if (!mem->is_pbl) > p = siw_get_upage(mem->umem, > @@ -97,11 +96,10 @@ static int siw_try_1seg(struct siw_iwarp_tx *c_tx, void *paddr) > if (unlikely(!p)) > return -EFAULT; > > - buffer = kmap_atomic(p); > - memcpy(paddr + part, buffer, > - bytes - part); > - kunmap_atomic(buffer); > + buffer = kmap(p); > + memcpy(paddr + part, buffer, bytes - part); > } > + kunmap(p); > } > } > return (int)bytes; > -- > 2.17.2 >
-----"Steve Wise" <larrystevenwise@gmail.com> wrote: ----- >To: "Bernard Metzler" <bmt@zurich.ibm.com> >From: "Steve Wise" <larrystevenwise@gmail.com> >Date: 09/07/2019 12:31AM >Cc: linux-rdma@vger.kernel.org, dledford@redhat.com >Subject: [EXTERNAL] Re: [PATCH] RDMA/siw: Relax from kmap_atomic() >use in TX path > >Hey Bernard, is the code below called directly from the driver’s >post_send function? If so it must use atomic...I think. > Hey Steve, Only a kernel TX thread executes the TX path. It is not executed directly from the drivers post_send() method, which only queues work for TX processing and wakes up the TX thread if it currently does not run. The single exception is TX processing out of a user space application context, if no TX thread is currently running, but only for a small burst. In any case, all TX processing is done out of a non-atomic context. Best, Bernard. >Stevo > >> On Sep 6, 2019, at 6:18 AM, Bernard Metzler <bmt@zurich.ibm.com> >wrote: >> >> Since the transmit path is never executed in an atomic >> context, we do not need kmap_atomic() and can always >> use less demanding kmap(). >> >> Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com> >> --- >> drivers/infiniband/sw/siw/siw_qp_tx.c | 12 +++++------- >> 1 file changed, 5 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c >b/drivers/infiniband/sw/siw/siw_qp_tx.c >> index 8e72f955921d..5d97bba0ce6d 100644 >> --- a/drivers/infiniband/sw/siw/siw_qp_tx.c >> +++ b/drivers/infiniband/sw/siw/siw_qp_tx.c >> @@ -76,16 +76,15 @@ static int siw_try_1seg(struct siw_iwarp_tx >*c_tx, void *paddr) >> if (unlikely(!p)) >> return -EFAULT; >> >> - buffer = kmap_atomic(p); >> + buffer = kmap(p); >> >> if (likely(PAGE_SIZE - off >= bytes)) { >> memcpy(paddr, buffer + off, bytes); >> - kunmap_atomic(buffer); >> } else { >> unsigned long part = bytes - (PAGE_SIZE - off); >> >> memcpy(paddr, buffer + off, part); >> - kunmap_atomic(buffer); >> + kunmap(p); >> >> if (!mem->is_pbl) >> p = siw_get_upage(mem->umem, >> @@ -97,11 +96,10 @@ static int siw_try_1seg(struct siw_iwarp_tx >*c_tx, void *paddr) >> if (unlikely(!p)) >> return -EFAULT; >> >> - buffer = kmap_atomic(p); >> - memcpy(paddr + part, buffer, >> - bytes - part); >> - kunmap_atomic(buffer); >> + buffer = kmap(p); >> + memcpy(paddr + part, buffer, bytes - part); >> } >> + kunmap(p); >> } >> } >> return (int)bytes; >> -- >> 2.17.2 >> > >
diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c b/drivers/infiniband/sw/siw/siw_qp_tx.c index 8e72f955921d..5d97bba0ce6d 100644 --- a/drivers/infiniband/sw/siw/siw_qp_tx.c +++ b/drivers/infiniband/sw/siw/siw_qp_tx.c @@ -76,16 +76,15 @@ static int siw_try_1seg(struct siw_iwarp_tx *c_tx, void *paddr) if (unlikely(!p)) return -EFAULT; - buffer = kmap_atomic(p); + buffer = kmap(p); if (likely(PAGE_SIZE - off >= bytes)) { memcpy(paddr, buffer + off, bytes); - kunmap_atomic(buffer); } else { unsigned long part = bytes - (PAGE_SIZE - off); memcpy(paddr, buffer + off, part); - kunmap_atomic(buffer); + kunmap(p); if (!mem->is_pbl) p = siw_get_upage(mem->umem, @@ -97,11 +96,10 @@ static int siw_try_1seg(struct siw_iwarp_tx *c_tx, void *paddr) if (unlikely(!p)) return -EFAULT; - buffer = kmap_atomic(p); - memcpy(paddr + part, buffer, - bytes - part); - kunmap_atomic(buffer); + buffer = kmap(p); + memcpy(paddr + part, buffer, bytes - part); } + kunmap(p); } } return (int)bytes;
Since the transmit path is never executed in an atomic context, we do not need kmap_atomic() and can always use less demanding kmap(). Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com> --- drivers/infiniband/sw/siw/siw_qp_tx.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)