From: Bjorn Helgaas <helgaas@kernel.org>
To: Logan Gunthorpe <logang@deltatee.com>
Cc: linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-block@vger.kernel.org, linux-pci@vger.kernel.org,
linux-mm@kvack.org, iommu@lists.linux-foundation.org,
"Stephen Bates" <sbates@raithlin.com>,
"Christoph Hellwig" <hch@lst.de>,
"Dan Williams" <dan.j.williams@intel.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Christian König" <christian.koenig@amd.com>,
"Ira Weiny" <iweiny@intel.com>,
"John Hubbard" <jhubbard@nvidia.com>,
"Don Dutile" <ddutile@redhat.com>,
"Matthew Wilcox" <willy@infradead.org>,
"Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Jakowski Andrzej" <andrzej.jakowski@intel.com>,
"Minturn Dave B" <dave.b.minturn@intel.com>,
"Jason Ekstrand" <jason@jlekstrand.net>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Xiong Jianxin" <jianxin.xiong@intel.com>
Subject: Re: [RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn()
Date: Fri, 12 Mar 2021 14:39:36 -0600 [thread overview]
Message-ID: <20210312203936.GA2286981@bjorn-Precision-5520> (raw)
In-Reply-To: <20210311233142.7900-2-logang@deltatee.com>
On Thu, Mar 11, 2021 at 04:31:31PM -0700, Logan Gunthorpe wrote:
> In order to call this function from a dma_map function, it must not sleep.
> The only reason it does sleep so to allocate the seqbuf to print
> which devices are within the ACS path.
s/this function/upstream_bridge_distance_warn()/ ?
s/so to/is to/
Maybe the subject could say something about the purpose, e.g., allow
calling from atomic context or something? "Pass gfp_mask flags" sort
of restates what we can read from the patch, but without the
motivation of why this is useful.
> Switch the kmalloc call to use a passed in gfp_mask and don't print that
> message if the buffer fails to be allocated.
>
> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/pci/p2pdma.c | 21 +++++++++++----------
> 1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index 196382630363..bd89437faf06 100644
> --- a/drivers/pci/p2pdma.c
> +++ b/drivers/pci/p2pdma.c
> @@ -267,7 +267,7 @@ static int pci_bridge_has_acs_redir(struct pci_dev *pdev)
>
> static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
> {
> - if (!buf)
> + if (!buf || !buf->buffer)
> return;
>
> seq_buf_printf(buf, "%s;", pci_name(pdev));
> @@ -495,25 +495,26 @@ upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
>
> static enum pci_p2pdma_map_type
> upstream_bridge_distance_warn(struct pci_dev *provider, struct pci_dev *client,
> - int *dist)
> + int *dist, gfp_t gfp_mask)
> {
> struct seq_buf acs_list;
> bool acs_redirects;
> int ret;
>
> - seq_buf_init(&acs_list, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE);
> - if (!acs_list.buffer)
> - return -ENOMEM;
> + seq_buf_init(&acs_list, kmalloc(PAGE_SIZE, gfp_mask), PAGE_SIZE);
>
> ret = upstream_bridge_distance(provider, client, dist, &acs_redirects,
> &acs_list);
> if (acs_redirects) {
> pci_warn(client, "ACS redirect is set between the client and provider (%s)\n",
> pci_name(provider));
> - /* Drop final semicolon */
> - acs_list.buffer[acs_list.len-1] = 0;
> - pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
> - acs_list.buffer);
> +
> + if (acs_list.buffer) {
> + /* Drop final semicolon */
> + acs_list.buffer[acs_list.len - 1] = 0;
> + pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
> + acs_list.buffer);
> + }
> }
>
> if (ret == PCI_P2PDMA_MAP_NOT_SUPPORTED) {
> @@ -566,7 +567,7 @@ int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
>
> if (verbose)
> ret = upstream_bridge_distance_warn(provider,
> - pci_client, &distance);
> + pci_client, &distance, GFP_KERNEL);
> else
> ret = upstream_bridge_distance(provider, pci_client,
> &distance, NULL, NULL);
> --
> 2.20.1
>
next prev parent reply other threads:[~2021-03-12 20:40 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-11 23:31 [RFC PATCH v2 00/11] Add support to dma_map_sg for P2PDMA Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn() Logan Gunthorpe
2021-03-12 20:39 ` Bjorn Helgaas [this message]
2021-03-12 20:53 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 02/11] PCI/P2PDMA: Avoid pci_get_slot() which sleeps Logan Gunthorpe
2021-03-12 20:57 ` Bjorn Helgaas
2021-03-12 21:37 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 03/11] PCI/P2PDMA: Attempt to set map_type if it has not been set Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 04/11] PCI/P2PDMA: Introduce pci_p2pdma_should_map_bus() and pci_p2pdma_bus_offset() Logan Gunthorpe
2021-03-13 1:38 ` Ira Weiny
2021-03-15 16:27 ` Logan Gunthorpe
2021-03-24 17:21 ` Jason Gunthorpe
2021-03-24 18:34 ` Christian König
2021-03-13 2:32 ` Ira Weiny
2021-03-15 16:30 ` Logan Gunthorpe
2021-03-16 8:14 ` Christoph Hellwig
2021-03-11 23:31 ` [RFC PATCH v2 05/11] lib/scatterlist: Add flag for indicating P2PDMA segments in an SGL Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 06/11] dma-direct: Support PCI P2PDMA pages in dma-direct map_sg Logan Gunthorpe
2021-03-12 15:52 ` Robin Murphy
2021-03-12 16:24 ` Logan Gunthorpe
2021-03-12 18:11 ` Robin Murphy
2021-03-12 18:27 ` Logan Gunthorpe
2021-03-16 7:58 ` Christoph Hellwig
2021-03-16 15:54 ` Logan Gunthorpe
2021-03-16 7:56 ` Christoph Hellwig
2021-03-16 8:11 ` Christoph Hellwig
2021-03-11 23:31 ` [RFC PATCH v2 07/11] dma-mapping: Add flags to dma_map_ops to indicate PCI P2PDMA support Logan Gunthorpe
2021-03-13 2:36 ` Ira Weiny
2021-03-15 16:33 ` Logan Gunthorpe
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 8:15 ` Christoph Hellwig
2021-03-11 23:31 ` [RFC PATCH v2 08/11] iommu/dma: Support PCI P2PDMA pages in dma-iommu map_sg Logan Gunthorpe
2021-03-12 15:52 ` Robin Murphy
2021-03-12 17:03 ` Logan Gunthorpe
2021-03-12 19:47 ` Robin Murphy
2021-03-12 20:06 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 09/11] block: Add BLK_STS_P2PDMA Logan Gunthorpe
2021-03-16 8:00 ` Christoph Hellwig
2021-03-16 16:02 ` Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 10/11] nvme-pci: Check DMA ops when indicating support for PCI P2PDMA Logan Gunthorpe
2021-03-11 23:31 ` [RFC PATCH v2 11/11] nvme-pci: Convert to using dma_map_sg for p2pdma pages Logan Gunthorpe
2021-03-11 23:59 ` Jason Gunthorpe
2021-03-12 1:37 ` Logan Gunthorpe
2021-03-12 15:51 ` [RFC PATCH v2 00/11] Add support to dma_map_sg for P2PDMA Robin Murphy
2021-03-12 16:18 ` Logan Gunthorpe
2021-03-12 17:46 ` Robin Murphy
2021-03-12 18:24 ` Logan Gunthorpe
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