| Message ID | 20230321154228.182769-4-sgarzare@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | vdpa_sim: add support for user VA | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On martedì 21 marzo 2023 16:42:23 CET Stefano Garzarella wrote: > kmap_atomic() is deprecated in favor of kmap_local_page() since commit > f3ba3c710ac5 ("mm/highmem: Provide kmap_local*"). > > With kmap_local_page() the mappings are per thread, CPU local, can take > page-faults, and can be called from any context (including interrupts). > Furthermore, the tasks can be preempted and, when they are scheduled to > run again, the kernel virtual addresses are restored and still valid. > > kmap_atomic() is implemented like a kmap_local_page() which also disables > page-faults and preemption (the latter only for !PREEMPT_RT kernels, > otherwise it only disables migration). > > The code within the mappings/un-mappings in getu16_iotlb() and > putu16_iotlb() don't depend on the above-mentioned side effects of > kmap_atomic(), so that mere replacements of the old API with the new one > is all that is required (i.e., there is no need to explicitly add calls > to pagefault_disable() and/or preempt_disable()). > > This commit reuses a "boiler plate" commit message from Fabio, who has > already did this change in several places. > FWIW, I can confirm that the conversions here are safe... Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Thanks, Fabio P.S.: I had to send this message again because my former contained HTML parts and so it was rejected by the mailing lists. I don't yet know how HTML crept into my text. > Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > > Notes: > v3: > - credited Fabio for the commit message > - added reference to the commit that deprecated kmap_atomic() [Jason] > v2: > - added this patch since checkpatch.pl complained about deprecation > of kmap_atomic() touched by next patch > > drivers/vhost/vringh.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > index a1e27da54481..0ba3ef809e48 100644 > --- a/drivers/vhost/vringh.c > +++ b/drivers/vhost/vringh.c > @@ -1220,10 +1220,10 @@ static inline int getu16_iotlb(const struct vringh > *vrh, if (ret < 0) > return ret; > > - kaddr = kmap_atomic(iov.bv_page); > + kaddr = kmap_local_page(iov.bv_page); > from = kaddr + iov.bv_offset; > *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from)); > - kunmap_atomic(kaddr); > + kunmap_local(kaddr); > > return 0; > } > @@ -1241,10 +1241,10 @@ static inline int putu16_iotlb(const struct vringh > *vrh, if (ret < 0) > return ret; > > - kaddr = kmap_atomic(iov.bv_page); > + kaddr = kmap_local_page(iov.bv_page); > to = kaddr + iov.bv_offset; > WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val)); > - kunmap_atomic(kaddr); > + kunmap_local(kaddr); > > return 0; > } > -- > 2.39.2
On Tue, Mar 21, 2023 at 11:42 PM Stefano Garzarella <sgarzare@redhat.com> wrote: > > kmap_atomic() is deprecated in favor of kmap_local_page() since commit > f3ba3c710ac5 ("mm/highmem: Provide kmap_local*"). > > With kmap_local_page() the mappings are per thread, CPU local, can take > page-faults, and can be called from any context (including interrupts). > Furthermore, the tasks can be preempted and, when they are scheduled to > run again, the kernel virtual addresses are restored and still valid. > > kmap_atomic() is implemented like a kmap_local_page() which also disables > page-faults and preemption (the latter only for !PREEMPT_RT kernels, > otherwise it only disables migration). > > The code within the mappings/un-mappings in getu16_iotlb() and > putu16_iotlb() don't depend on the above-mentioned side effects of > kmap_atomic(), so that mere replacements of the old API with the new one > is all that is required (i.e., there is no need to explicitly add calls > to pagefault_disable() and/or preempt_disable()). > > This commit reuses a "boiler plate" commit message from Fabio, who has > already did this change in several places. > > Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Thanks > --- > > Notes: > v3: > - credited Fabio for the commit message > - added reference to the commit that deprecated kmap_atomic() [Jason] > v2: > - added this patch since checkpatch.pl complained about deprecation > of kmap_atomic() touched by next patch > > drivers/vhost/vringh.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c > index a1e27da54481..0ba3ef809e48 100644 > --- a/drivers/vhost/vringh.c > +++ b/drivers/vhost/vringh.c > @@ -1220,10 +1220,10 @@ static inline int getu16_iotlb(const struct vringh *vrh, > if (ret < 0) > return ret; > > - kaddr = kmap_atomic(iov.bv_page); > + kaddr = kmap_local_page(iov.bv_page); > from = kaddr + iov.bv_offset; > *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from)); > - kunmap_atomic(kaddr); > + kunmap_local(kaddr); > > return 0; > } > @@ -1241,10 +1241,10 @@ static inline int putu16_iotlb(const struct vringh *vrh, > if (ret < 0) > return ret; > > - kaddr = kmap_atomic(iov.bv_page); > + kaddr = kmap_local_page(iov.bv_page); > to = kaddr + iov.bv_offset; > WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val)); > - kunmap_atomic(kaddr); > + kunmap_local(kaddr); > > return 0; > } > -- > 2.39.2 >
diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c index a1e27da54481..0ba3ef809e48 100644 --- a/drivers/vhost/vringh.c +++ b/drivers/vhost/vringh.c @@ -1220,10 +1220,10 @@ static inline int getu16_iotlb(const struct vringh *vrh, if (ret < 0) return ret; - kaddr = kmap_atomic(iov.bv_page); + kaddr = kmap_local_page(iov.bv_page); from = kaddr + iov.bv_offset; *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from)); - kunmap_atomic(kaddr); + kunmap_local(kaddr); return 0; } @@ -1241,10 +1241,10 @@ static inline int putu16_iotlb(const struct vringh *vrh, if (ret < 0) return ret; - kaddr = kmap_atomic(iov.bv_page); + kaddr = kmap_local_page(iov.bv_page); to = kaddr + iov.bv_offset; WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val)); - kunmap_atomic(kaddr); + kunmap_local(kaddr); return 0; }
kmap_atomic() is deprecated in favor of kmap_local_page() since commit f3ba3c710ac5 ("mm/highmem: Provide kmap_local*"). With kmap_local_page() the mappings are per thread, CPU local, can take page-faults, and can be called from any context (including interrupts). Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and still valid. kmap_atomic() is implemented like a kmap_local_page() which also disables page-faults and preemption (the latter only for !PREEMPT_RT kernels, otherwise it only disables migration). The code within the mappings/un-mappings in getu16_iotlb() and putu16_iotlb() don't depend on the above-mentioned side effects of kmap_atomic(), so that mere replacements of the old API with the new one is all that is required (i.e., there is no need to explicitly add calls to pagefault_disable() and/or preempt_disable()). This commit reuses a "boiler plate" commit message from Fabio, who has already did this change in several places. Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- Notes: v3: - credited Fabio for the commit message - added reference to the commit that deprecated kmap_atomic() [Jason] v2: - added this patch since checkpatch.pl complained about deprecation of kmap_atomic() touched by next patch drivers/vhost/vringh.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)