From: Al Viro <viro@zeniv.linux.org.uk>
To: op-tee@lists.trustedfirmware.org
Subject: Re: [PATCH 3/4] tee: Remove call to get_kernel_pages()
Date: Sun, 02 Oct 2022 00:46:52 +0000 [thread overview]
Message-ID: <YzjfcW6OGcPP075q@ZenIV> (raw)
In-Reply-To: <20221002002326.946620-4-ira.weiny@intel.com>
[-- Attachment #1: Type: text/plain, Size: 986 bytes --]
On Sat, Oct 01, 2022 at 05:23:25PM -0700, ira.weiny(a)intel.com wrote:
> kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> @@ -38,12 +39,12 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count,
> for (n = 0; n < page_count; n++) {
> kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> kiov[n].iov_len = PAGE_SIZE;
> + pages[n] = virt_to_page(kiov[n].iov_base);
> + get_page(pages[n]);
> }
> -
> - rc = get_kernel_pages(kiov, page_count, 0, pages);
> kfree(kiov);
IDGI. The only thing in kiov[...] you are every reading is
->iov_base. And you fetch it once, right after the assignment.
Why bother with allocating the array at all?
pages[n] = virt_to_page((void *)start + n * PAGE_SIZE);
would do just as well, not to mention the fact that since you reject
vmalloc and kmap, you might simply do
page = virt_to_page(start);
for (int n = 0; n < page_count; n++)
get_page(pages[n] = page + n);
instead...
WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv.linux.org.uk>
To: ira.weiny@intel.com
Cc: Jens Wiklander <jens.wiklander@linaro.org>,
Sumit Garg <sumit.garg@linaro.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
Christoph Hellwig <hch@lst.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
op-tee@lists.trustedfirmware.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 3/4] tee: Remove call to get_kernel_pages()
Date: Sun, 2 Oct 2022 01:46:41 +0100 [thread overview]
Message-ID: <YzjfcW6OGcPP075q@ZenIV> (raw)
In-Reply-To: <20221002002326.946620-4-ira.weiny@intel.com>
On Sat, Oct 01, 2022 at 05:23:25PM -0700, ira.weiny@intel.com wrote:
> kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
> @@ -38,12 +39,12 @@ static int shm_get_kernel_pages(unsigned long start, size_t page_count,
> for (n = 0; n < page_count; n++) {
> kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
> kiov[n].iov_len = PAGE_SIZE;
> + pages[n] = virt_to_page(kiov[n].iov_base);
> + get_page(pages[n]);
> }
> -
> - rc = get_kernel_pages(kiov, page_count, 0, pages);
> kfree(kiov);
IDGI. The only thing in kiov[...] you are every reading is
->iov_base. And you fetch it once, right after the assignment.
Why bother with allocating the array at all?
pages[n] = virt_to_page((void *)start + n * PAGE_SIZE);
would do just as well, not to mention the fact that since you reject
vmalloc and kmap, you might simply do
page = virt_to_page(start);
for (int n = 0; n < page_count; n++)
get_page(pages[n] = page + n);
instead...
next prev parent reply other threads:[~2022-10-02 0:46 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-02 0:23 [PATCH 0/4] Remove get_kernel_pages() ira.weiny
2022-10-02 0:23 ` ira.weiny
2022-10-02 0:23 ` [PATCH 1/4] highmem: Enhance is_kmap_addr() to check kmap_local_page() mappings ira.weiny
2022-10-02 0:23 ` ira.weiny
2022-10-02 0:23 ` [PATCH 2/4] tee: Remove vmalloc page support ira.weiny
2022-10-02 0:23 ` ira.weiny
2022-10-03 6:41 ` Jens Wiklander
2022-10-03 6:41 ` Jens Wiklander
2022-10-03 6:57 ` Sumit Garg
2022-10-03 6:57 ` Sumit Garg
2022-10-05 3:28 ` Phil Chang (張世勳)
2022-10-05 3:28 ` Phil Chang (張世勳)
2022-10-02 0:23 ` [PATCH 3/4] tee: Remove call to get_kernel_pages() ira.weiny
2022-10-02 0:23 ` ira.weiny
2022-10-02 0:46 ` Al Viro [this message]
2022-10-02 0:46 ` Al Viro
2022-10-02 2:30 ` Ira Weiny
2022-10-02 2:30 ` Ira Weiny
2022-10-03 7:17 ` Christoph Hellwig
2022-10-03 7:17 ` Christoph Hellwig
2022-10-03 15:02 ` Ira Weiny
2022-10-03 15:02 ` Ira Weiny
2022-10-02 0:23 ` [PATCH 4/4] mm: Remove get_kernel_pages() ira.weiny
2022-10-02 0:23 ` ira.weiny
2022-10-03 20:28 ` John Hubbard
2022-10-03 20:28 ` John Hubbard
2022-10-03 9:25 ` [PATCH 0/4] " Sumit Garg
2022-10-03 9:25 ` Sumit Garg
[not found] < <CAFA6WYN+3inY6MYrMFY0qhmifCYtj_immFMFN6jC1BamQCYGWQ@mail.gmail.com>
2022-10-03 15:22 ` Ira Weiny
2022-10-03 15:22 ` Ira Weiny
2022-10-04 6:32 ` Sumit Garg
2022-10-04 6:32 ` Sumit Garg
[not found] <=?utf-8?q?=3CTYZPR03MB65279558CC22F5130B710EA8FB5D9=40TYZPR03MB?= =?utf-8?q?6527=2Eapcprd03=2Eprod=2Eoutlook=2Ecom=3E?=>
2022-10-06 6:23 ` [PATCH 2/4] tee: Remove vmalloc page support Sumit Garg
2022-10-06 6:23 ` Sumit Garg
[not found] < <CAFA6WYMT9S1Di6DN_UXc823f0ZTkqerE1PB=oG6wmfx28vEbDg@mail.gmail.com>
2022-10-06 18:19 ` Ira Weiny
2022-10-06 18:19 ` Ira Weiny
2022-10-06 18:20 ` Linus Torvalds
2022-10-06 18:20 ` Linus Torvalds
[not found] < <CAHk-=whVyH-wSWLd=Zn4rwo+91T+qzRvfMPC2yFX98GxykOqOw@mail.gmail.com>
2022-10-07 8:12 ` Jens Wiklander
2022-10-07 8:12 ` Jens Wiklander
2022-10-10 7:42 ` Christoph Hellwig
2022-10-10 7:42 ` Christoph Hellwig
2022-10-10 17:20 ` Linus Torvalds
2022-10-10 17:20 ` Linus Torvalds
[not found] < <CAHk-=whvmR98OHdYf4yOJgp86hq0VMVXJ9b1Qk7P_Rjq_=HU+A@mail.gmail.com>
2022-10-10 17:57 ` Al Viro
2022-10-10 17:57 ` Al Viro
[not found] < <CAHUa44GkTLCzuSij5FbjBXFBM1CCQROtrCtHHtj70ZRi-3K7uA@mail.gmail.com>
2022-12-16 0:41 ` Ira Weiny
2022-12-16 0:41 ` Ira Weiny
2022-12-16 5:09 ` Sumit Garg
2022-12-16 5:09 ` Sumit Garg
2022-12-16 7:06 ` Christoph Hellwig
2022-12-16 7:06 ` Christoph Hellwig
[not found] < <CAFA6WYNMRymyqkqfASYAPVoL0iR2kw0h9YKZ1gBTdeSuHMOAtQ@mail.gmail.com>
2022-12-16 8:45 ` Sumit Garg
2022-12-16 8:45 ` Sumit Garg
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