linux-kernel - [PATCH 01/16] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance

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Message-Id: <20210408170123.8788-2-logang@deltatee.com>
Date:   Thu,  8 Apr 2021 11:01:08 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-block@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-mm@...ck.org, iommu@...ts.linux-foundation.org
Cc:     Stephen Bates <sbates@...thlin.com>,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Christian König <christian.koenig@....com>,
        John Hubbard <jhubbard@...dia.com>,
        Don Dutile <ddutile@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Jakowski Andrzej <andrzej.jakowski@...el.com>,
        Minturn Dave B <dave.b.minturn@...el.com>,
        Jason Ekstrand <jason@...kstrand.net>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Xiong Jianxin <jianxin.xiong@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Robin Murphy <robin.murphy@....com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 01/16] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn()

In order to call upstream_bridge_distance_warn() from a dma_map function,
it must not sleep. The only reason it does sleep is to allocate the seqbuf
to print which devices are within the ACS path.

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@...tatee.com>
Acked-by: Bjorn Helgaas <bhelgaas@...gle.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