From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To: Mauro Carvalho Chehab <mchehab@kernel.org>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Hans Verkuil <hverkuil-cisco@xs4all.nl>,
Tsuchiya Yuto <kitakar@gmail.com>,
Martiros Shakhzadyan <vrzh@vrzh.net>,
Hans de Goede <hdegoede@redhat.com>,
linux-media@vger.kernel.org, linux-staging@lists.linux.dev,
linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
outreachy@lists.linux.dev
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Subject: [PATCH] staging: media: atomisp: Use kmap_local_page() in hmm_store()
Date: Thu, 14 Apr 2022 00:55:31 +0200 [thread overview]
Message-ID: <20220413225531.9425-1-fmdefrancesco@gmail.com> (raw)
The use of kmap() is being deprecated in favor of kmap_local_page()
where it is feasible. The same is true for kmap_atomic().
In file pci/hmm/hmm.c, function hmm_store() test if we are in atomic
context and, if so, it calls kmap_atomic(), if not, it calls kmap().
First of all, in_atomic() shouldn't be used in drivers. This macro
cannot always detect atomic context; in particular, it cannot know
about held spinlocks in non-preemptible kernels.
Notwithstanding what it is said above, this code doesn't need to care
whether or not it is executing in atomic context. It can simply use
kmap_local_page() / kunmap_local() that can instead do the mapping /
unmapping regardless of the context.
With kmap_local_page(), the mapping is per thread, CPU local and not
globally visible. Therefore, hmm_store()() is a function where the use
of kmap_local_page() in place of both kmap() and kmap_atomic() is
correctly suited.
Convert the calls of kmap() / kunmap() and kmap_atomic() /
kunmap_atomic() to kmap_local_page() / kunmap_local() and drop the
unnecessary tests which test if the code is in atomic context.
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
drivers/staging/media/atomisp/pci/hmm/hmm.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/drivers/staging/media/atomisp/pci/hmm/hmm.c b/drivers/staging/media/atomisp/pci/hmm/hmm.c
index 46ac082cd3f1..54188197c3dc 100644
--- a/drivers/staging/media/atomisp/pci/hmm/hmm.c
+++ b/drivers/staging/media/atomisp/pci/hmm/hmm.c
@@ -482,10 +482,7 @@ int hmm_store(ia_css_ptr virt, const void *data, unsigned int bytes)
idx = (virt - bo->start) >> PAGE_SHIFT;
offset = (virt - bo->start) - (idx << PAGE_SHIFT);
- if (in_atomic())
- des = (char *)kmap_atomic(bo->page_obj[idx].page);
- else
- des = (char *)kmap(bo->page_obj[idx].page);
+ des = (char *)kmap_local_page(bo->page_obj[idx].page);
if (!des) {
dev_err(atomisp_dev,
@@ -512,14 +509,7 @@ int hmm_store(ia_css_ptr virt, const void *data, unsigned int bytes)
clflush_cache_range(des, len);
- if (in_atomic())
- /*
- * Note: kunmap_atomic requires return addr from
- * kmap_atomic, not the page. See linux/highmem.h
- */
- kunmap_atomic(des - offset);
- else
- kunmap(bo->page_obj[idx].page);
+ kunmap_local(des);
}
return 0;
--
2.34.1
next reply other threads:[~2022-04-13 22:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-13 22:55 Fabio M. De Francesco [this message]
2022-04-14 0:44 ` [PATCH] staging: media: atomisp: Use kmap_local_page() in hmm_store() Alison Schofield
2022-04-14 1:54 ` Ira Weiny
2022-04-14 7:03 ` Julia Lawall
2022-04-14 9:03 ` Fabio M. De Francesco
2022-04-14 9:12 ` Julia Lawall
2022-04-14 9:41 ` Fabio M. De Francesco
2022-04-15 0:37 ` Ira Weiny
2022-04-15 1:08 ` Fabio M. De Francesco
2022-04-20 11:07 ` Hans de Goede
2022-04-25 18:29 ` Fabio M. De Francesco
2022-04-29 13:46 ` Fabio M. De Francesco
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