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| author | Logan Gunthorpe <logang@deltatee.com> | 2021-06-10 18:06:05 +0200 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2021-06-11 01:01:41 +0200 |
| commit | e4ece59abd70d8f54e2163274dc996bb442832a6 (patch) | |
| tree | 9b8c0159fbd6f5a66a2ac779752ea052344d36e5 | |
| parent | PCI/P2PDMA: Rename upstream_bridge_distance() and rework doc (diff) | |
| download | linux-e4ece59abd70d8f54e2163274dc996bb442832a6.tar.xz linux-e4ece59abd70d8f54e2163274dc996bb442832a6.zip | |
PCI/P2PDMA: Collect acs list in stack buffer to avoid sleeping
In order to call the calc_map_type_and_dist_warn() function from a dma_map
operation, the function must not sleep. The only reason it sleeps is to
allocate memory for the seq_buf to print a verbose warning telling the user
how to disable ACS for that path.
Instead of allocating the memory with kmalloc(), allocate a smaller buffer
on the stack. A 128 byte buffer is enough to print 10 PCI device names. A
system with 10 bridge ports between two devices that have ACS enabled would
be unusually large, so this should still be a reasonable limit.
This also cleans up the awkward (and broken) return with -ENOMEM which
contradicts the return type and the caller was not prepared for.
Link: https://lore.kernel.org/r/20210610160609.28447-3-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
| -rw-r--r-- | drivers/pci/p2pdma.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index a860137fac89..109bd7321962 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -502,11 +502,10 @@ calc_map_type_and_dist_warn(struct pci_dev *provider, struct pci_dev *client, { struct seq_buf acs_list; bool acs_redirects; + char buf[128]; 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, buf, sizeof(buf)); ret = calc_map_type_and_dist(provider, client, dist, &acs_redirects, &acs_list); @@ -524,8 +523,6 @@ calc_map_type_and_dist_warn(struct pci_dev *provider, struct pci_dev *client, pci_name(provider)); } - kfree(acs_list.buffer); - return ret; } |