Re: [RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn()
On 2021-03-12 1:39 p.m., Bjorn Helgaas wrote: 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 Acked-by: Bjorn Helgaas Thanks! I'll apply these changes for any future postings. Logan ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn()
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
Acked-by: Bjorn Helgaas
> ---
> 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(_list, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE);
> - if (!acs_list.buffer)
> - return -ENOMEM;
> + seq_buf_init(_list, kmalloc(PAGE_SIZE, gfp_mask), PAGE_SIZE);
>
> ret = upstream_bridge_distance(provider, client, dist, _redirects,
> _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, );
> + pci_client, , GFP_KERNEL);
> else
> ret = upstream_bridge_distance(provider, pci_client,
> , NULL, NULL);
> --
> 2.20.1
>
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[RFC PATCH v2 01/11] PCI/P2PDMA: Pass gfp_mask flags to upstream_bridge_distance_warn()
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.
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
---
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(_list, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE);
- if (!acs_list.buffer)
- return -ENOMEM;
+ seq_buf_init(_list, kmalloc(PAGE_SIZE, gfp_mask), PAGE_SIZE);
ret = upstream_bridge_distance(provider, client, dist, _redirects,
_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, );
+ pci_client, , GFP_KERNEL);
else
ret = upstream_bridge_distance(provider, pci_client,
, NULL, NULL);
--
2.20.1
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