From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: linux-kernel@vger.kernel.org, opendmb@gmail.com,
Christoph Hellwig <hch@lst.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
"open list:SWIOTLB SUBSYSTEM" <iommu@lists.linux-foundation.org>
Subject: Re: [PATCH] swiotlb: Make SWIOTLB_NO_FORCE perform no allocation
Date: Fri, 19 Mar 2021 01:01:11 -0400 [thread overview]
Message-ID: <YFQwFwZbVJoG0DpZ@Konrads-MacBook-Pro.local> (raw)
In-Reply-To: <20210319040055.183433-1-f.fainelli@gmail.com>
On Thu, Mar 18, 2021 at 09:00:54PM -0700, Florian Fainelli wrote:
> When SWIOTLB_NO_FORCE is used, there should really be no allocations of
> io_tlb_nslabs to occur since we are not going to use those slabs. If a
> platform was somehow setting swiotlb_no_force and a later call to
> swiotlb_init() was to be made we would still be proceeding with
> allocating the default SWIOTLB size (64MB), whereas if swiotlb=noforce
> was set on the kernel command line we would have only allocated 2KB.
>
> This would be inconsistent and the point of initializing io_tlb_nslabs
> to 1, was to avoid hitting the test for io_tlb_nslabs being 0/not
> initialized.
Could you rebase this on devel/for-linus-5.13 in
git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb.git
please?
>
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
> kernel/dma/swiotlb.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index c10e855a03bc..526c8321b76f 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -121,12 +121,10 @@ setup_io_tlb_npages(char *str)
> }
> if (*str == ',')
> ++str;
> - if (!strcmp(str, "force")) {
> + if (!strcmp(str, "force"))
> swiotlb_force = SWIOTLB_FORCE;
> - } else if (!strcmp(str, "noforce")) {
> + else if (!strcmp(str, "noforce"))
> swiotlb_force = SWIOTLB_NO_FORCE;
> - io_tlb_nslabs = 1;
> - }
>
> return 0;
> }
> @@ -284,6 +282,9 @@ swiotlb_init(int verbose)
> unsigned char *vstart;
> unsigned long bytes;
>
> + if (swiotlb_force == SWIOTLB_NO_FORCE)
> + goto out;
> +
> if (!io_tlb_nslabs) {
> io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
> io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
> @@ -302,6 +303,7 @@ swiotlb_init(int verbose)
> io_tlb_start = 0;
> }
> pr_warn("Cannot allocate buffer");
> +out:
> no_iotlb_memory = true;
> }
>
> --
> 2.25.1
>
next prev parent reply other threads:[~2021-03-19 5:02 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-18 19:18 [PATCH] swiotlb: Add swiotlb=off to disable SWIOTLB Florian Fainelli
2021-03-18 19:22 ` Florian Fainelli
2021-03-18 19:34 ` Robin Murphy
2021-03-18 19:43 ` Florian Fainelli
2021-03-18 19:53 ` Robin Murphy
2021-03-18 21:31 ` Florian Fainelli
2021-03-18 23:35 ` Robin Murphy
2021-03-19 0:48 ` Florian Fainelli
2021-03-19 2:34 ` Konrad Rzeszutek Wilk
2021-03-19 4:00 ` [PATCH] swiotlb: Make SWIOTLB_NO_FORCE perform no allocation Florian Fainelli
2021-03-19 5:01 ` Konrad Rzeszutek Wilk [this message]
2021-03-21 3:37 ` [PATCH v2] " Florian Fainelli
2021-03-22 7:46 ` Christoph Hellwig
2021-03-23 1:53 ` [PATCH v3] " Florian Fainelli
2021-03-24 8:42 ` Christoph Hellwig
2021-04-09 3:13 ` Florian Fainelli
2021-04-09 19:32 ` Konrad Rzeszutek Wilk
2021-04-09 20:33 ` Florian Fainelli
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