Re: [RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn()
From: Bjorn Helgaas <helgaas@kernel.org>
Date: 2021-03-12 20:40:29
Also in:
linux-iommu, linux-mm, linux-nvme, linux-pci, lkml
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>
quoted hunk ↗ jump to hunk
--- 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