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Message-Id: <OF951DAF0B.941A938D-ON002586FD.003F1610-002586FD.00504522@notes.na.collabserv.com>
Date: Wed, 23 Jun 2021 14:36:45 +0000
From: "Bernard Metzler" <BMT@...ich.ibm.com>
To: "ira.weiny" <ira.weiny@...el.com>
Cc: "Jason Gunthorpe" <jgg@...pe.ca>,
"Mike Marciniszyn" <mike.marciniszyn@...nelisnetworks.com>,
"Dennis Dalessandro" <dennis.dalessandro@...nelisnetworks.com>,
"Doug Ledford" <dledford@...hat.com>,
"Faisal Latif" <faisal.latif@...el.com>,
"Shiraz Saleem" <shiraz.saleem@...el.com>,
"Kamal Heib" <kheib@...hat.com>,
"linux-rdma" <linux-rdma@...r.kernel.org>,
"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2] RDMA/siw: Convert siw_tx_hdt() to kmap_local_page()
-----ira.weiny@...el.com wrote: -----
>To: "Jason Gunthorpe" <jgg@...pe.ca>
>From: ira.weiny@...el.com
>Date: 06/22/2021 10:35PM
>Cc: "Ira Weiny" <ira.weiny@...el.com>, "Mike Marciniszyn"
><mike.marciniszyn@...nelisnetworks.com>, "Dennis Dalessandro"
><dennis.dalessandro@...nelisnetworks.com>, "Doug Ledford"
><dledford@...hat.com>, "Faisal Latif" <faisal.latif@...el.com>,
>"Shiraz Saleem" <shiraz.saleem@...el.com>, "Bernard Metzler"
><bmt@...ich.ibm.com>, "Kamal Heib" <kheib@...hat.com>,
>linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org
>Subject: [EXTERNAL] [PATCH V2] RDMA/siw: Convert siw_tx_hdt() to
>kmap_local_page()
>
>From: Ira Weiny <ira.weiny@...el.com>
>
>kmap() is being deprecated and will break uses of device dax after
>PKS
>protection is introduced.[1]
>
>The use of kmap() in siw_tx_hdt() is all thread local therefore
>kmap_local_page() is a sufficient replacement and will work with
>pgmap
>protected pages when those are implemented.
>
>siw_tx_hdt() tracks pages used in a page_array. It uses that array
>to
>unmap pages which were mapped on function exit. Not all entries in
>the
>array are mapped and this is tracked in kmap_mask.
>
>kunmap_local() takes a mapped address rather than a page. Alter
>siw_unmap_pages() to take the iov array to reuse the iov_base address
>of
>each mapping. Use PAGE_MASK to get the proper address for
>kunmap_local().
>
>kmap_local_page() mappings are tracked in a stack and must be
>unmapped
>in the opposite order they were mapped in. Because segments are
>mapped
>into the page array in increasing index order, modify
>siw_unmap_pages()
>to unmap pages in decreasing order.
>
>Use kmap_local_page() instead of kmap() to map pages in the
>page_array.
>
>[1]
>INVALID URI REMOVED
>lkml_20201009195033.3208459-2D59-2Dira.weiny-40intel.com_&d=DwIDAg&c=
>jf_iaSHvJObTbx-siA1ZOg&r=2TaYXQ0T-r8ZO1PP1alNwU_QJcRRLfmYTAgd3QCvqSc&
>m=ujJBVqPLdVdVxXvOu_PlFL3NVC0Znds3FgxyrtWJtwM&s=WZIBAdwlCqPIRjsNOGlly
>gQ6Hsug6ObgrWgO_nvBGyc&e=
>
>Signed-off-by: Ira Weiny <ira.weiny@...el.com>
>
>---
>Changes for V2:
> From Bernard
> Reuse iov[].iov_base rather than declaring another array of
> pointers and preserve the use of kmap_mask to know which iov's
> were kmapped.
>
>---
> drivers/infiniband/sw/siw/siw_qp_tx.c | 32
>+++++++++++++++++----------
> 1 file changed, 20 insertions(+), 12 deletions(-)
>
>diff --git a/drivers/infiniband/sw/siw/siw_qp_tx.c
>b/drivers/infiniband/sw/siw/siw_qp_tx.c
>index db68a10d12cd..fd3b9e6a67d7 100644
>--- a/drivers/infiniband/sw/siw/siw_qp_tx.c
>+++ b/drivers/infiniband/sw/siw/siw_qp_tx.c
>@@ -396,13 +396,20 @@ static int siw_0copy_tx(struct socket *s,
>struct page **page,
>
> #define MAX_TRAILER (MPA_CRC_SIZE + 4)
>
>-static void siw_unmap_pages(struct page **pp, unsigned long
>kmap_mask)
>+static void siw_unmap_pages(struct kvec *iov, unsigned long
>kmap_mask, int len)
> {
>- while (kmap_mask) {
>- if (kmap_mask & BIT(0))
>- kunmap(*pp);
>- pp++;
>- kmap_mask >>= 1;
>+ int i;
>+
>+ /*
>+ * Work backwards through the array to honor the kmap_local_page()
>+ * ordering requirements.
>+ */
>+ for (i = (len-1); i >= 0; i--) {
>+ if (kmap_mask & BIT(i)) {
>+ unsigned long addr = (unsigned long)iov[i].iov_base;
>+
>+ kunmap_local((void *)(addr & PAGE_MASK));
>+ }
> }
> }
>
>@@ -498,7 +505,7 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx,
>struct socket *s)
> p = siw_get_upage(mem->umem,
> sge->laddr + sge_off);
> if (unlikely(!p)) {
>- siw_unmap_pages(page_array, kmap_mask);
>+ siw_unmap_pages(iov, kmap_mask, MAX_ARRAY);
> wqe->processed -= c_tx->bytes_unsent;
> rv = -EFAULT;
> goto done_crc;
>@@ -506,11 +513,12 @@ static int siw_tx_hdt(struct siw_iwarp_tx
>*c_tx, struct socket *s)
> page_array[seg] = p;
>
> if (!c_tx->use_sendpage) {
>- iov[seg].iov_base = kmap(p) + fp_off;
>- iov[seg].iov_len = plen;
>+ void *kaddr = kmap_local_page(page_array[seg]);
we can use 'kmap_local_page(p)' here
>
> /* Remember for later kunmap() */
> kmap_mask |= BIT(seg);
>+ iov[seg].iov_base = kaddr + fp_off;
>+ iov[seg].iov_len = plen;
>
> if (do_crc)
> crypto_shash_update(
>@@ -518,7 +526,7 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx,
>struct socket *s)
> iov[seg].iov_base,
> plen);
This patch does not apply for me. Would I have to install first
your [Patch 3/4] -- since the current patch references kmap_local_page()
already? Maybe it is better to apply if it would be just one siw
related patch in that series?
> } else if (do_crc) {
>- kaddr = kmap_local_page(p);
>+ kaddr = kmap_local_page(page_array[seg]);
using 'kmap_local_page(p)' as you had it is straightforward
and I would prefer it.
> crypto_shash_update(c_tx->mpa_crc_hd,
> kaddr + fp_off,
> plen);
>@@ -542,7 +550,7 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx,
>struct socket *s)
>
> if (++seg > (int)MAX_ARRAY) {
> siw_dbg_qp(tx_qp(c_tx), "to many fragments\n");
>- siw_unmap_pages(page_array, kmap_mask);
>+ siw_unmap_pages(iov, kmap_mask, MAX_ARRAY);
to minimize the iterations over the byte array in 'siw_unmap_pages()',
we may pass seg-1 instead of MAX_ARRAY
> wqe->processed -= c_tx->bytes_unsent;
> rv = -EMSGSIZE;
> goto done_crc;
>@@ -593,7 +601,7 @@ static int siw_tx_hdt(struct siw_iwarp_tx *c_tx,
>struct socket *s)
> } else {
> rv = kernel_sendmsg(s, &msg, iov, seg + 1,
> hdr_len + data_len + trl_len);
>- siw_unmap_pages(page_array, kmap_mask);
>+ siw_unmap_pages(iov, kmap_mask, MAX_ARRAY);
to minimize the iterations over the byte array in 'siw_unmap_pages()',
we may pass seg instead of MAX_ARRAY
> }
> if (rv < (int)hdr_len) {
> /* Not even complete hdr pushed or negative rv */
>--
>2.28.0.rc0.12.gb6a658bd00c9
>
>
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