Re: [PATCH for-next] RDMA/efa: Add AH usage counter with sysfs exposure

[Leon Romanovsky <leon@kernel.org>]

On Thu, Feb 12, 2026 at 08:52:41AM +0200, Gal Pressman wrote:
> On 11/02/2026 15:13, Jason Gunthorpe wrote:
> > On Wed, Feb 11, 2026 at 01:10:48PM +0000, Tom Sela wrote:
> >> +static ssize_t ah_count_show(struct device *dev, struct device_attribute *attr, char *buf)
> >> +{
> >> +	struct efa_dev *efa_dev = pci_get_drvdata(to_pci_dev(dev));
> >> +
> >> +	return sysfs_emit(buf, "%lld\n", atomic64_read(&efa_dev->ah_count));
> >> +}
> >> +
> >> +static DEVICE_ATTR_RO(ah_count);
> >> +
> >> +int efa_sysfs_init(struct efa_dev *dev)
> >> +{
> >> +	struct device *device = &dev->pdev->dev;
> >> +
> >> +	if (device_create_file(device, &dev_attr_ah_count))
> >> +		dev_err(device, "Failed to create AH count sysfs file\n");
> > 
> > This is not the right way to use sysfs in rdma drivers.
> > 
> > Also we have netlink counters as the prefered approach why are you
> > using sysfs?
> 
> Yes, and EFA already supports stats reporting, the sysfs choice is strange..
> 
> BTW, isn't this something that can be added to restrack?

Unlikely. Most drivers that implement such counters were written long before
bpftrace became widely used. I don't think modern drivers should carry these
counters, as they are trivial to collect without requiring any kernel changes.
This is especially true for EFA, which does not support kverbs.

Thanks.