On 2021-05-11 10:05 a.m., Don Dutile wrote: > On 5/1/21 11:58 PM, John Hubbard wrote: >> On 4/8/21 10:01 AM, Logan Gunthorpe wrote: >>> 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@xxxxxxxxxxxx> >>> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> >>> --- >>> 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) >> >> This is not great, sort of from an overall design point of view, even though >> it makes the rest of the patch work. See below for other ideas, that will >> avoid the need for this sort of odd point fix. >> > +1. > In fact, I didn't see how the kmalloc was changed... you refactored the code to pass-in the > GFP_KERNEL that was originally hard-coded into upstream_bridge_distance_warn(); > I don't see how that avoided the kmalloc() call. > in fact, I also see you lost a failed kmalloc() check, so it seems to have taken a step back. I've changed this in v2 to just use some memory allocated on the stack. Avoids this argument all together. Logan