Messages in this thread | | | From | Vincent MAILHOL <> | Date | Thu, 24 Nov 2022 01:08:10 +0900 | Subject | Re: [RFC PATCH] net: devlink: devlink_nl_info_fill: populate default information |
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On Wed. 23 Nov. 2022 at 21:10, Jiri Pirko <jiri@nvidia.com> wrote: > Wed, Nov 23, 2022 at 12:00:44PM CET, mailhol.vincent@wanadoo.fr wrote: > >On Wed. 23 nov. 2022 à 18:46, Jiri Pirko <jiri@nvidia.com> wrote: > >> Tue, Nov 22, 2022 at 04:49:34PM CET, mailhol.vincent@wanadoo.fr wrote: > >> >Some piece of information are common to the vast majority of the > >> >devices. Examples are: > >> > > >> > * the driver name. > >> > * the serial number of a USB device. > >> > > >> >Modify devlink_nl_info_fill() to retrieve those information so that > >> >the drivers do not have to. Rationale: factorize code. > >> > > >> >Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> > >> >--- > >> >I am sending this as an RFC because I just started to study devlink. > >> > > >> >I can see a parallel with ethtool for which the core will fill > >> >whatever it can. c.f.: > >> >commit f20a0a0519f3 ("ethtool: doc: clarify what drivers can implement in their get_drvinfo()") > >> >Link: https://git.kernel.org/netdev/net-next/c/f20a0a0519f3 > >> > > >> >I think that devlink should do the same. > >> > > >> >Right now, I identified two fields. If this RFC receive positive > >> >feedback, I will iron it up and try to see if there is more that can > >> >be filled by default. > >> > > >> >Thank you for your comments. > >> >--- > >> > net/core/devlink.c | 36 ++++++++++++++++++++++++++++++++++++ > >> > 1 file changed, 36 insertions(+) > >> > > >> >diff --git a/net/core/devlink.c b/net/core/devlink.c > >> >index 7f789bbcbbd7..1908b360caf7 100644 > >> >--- a/net/core/devlink.c > >> >+++ b/net/core/devlink.c > >> >@@ -18,6 +18,7 @@ > >> > #include <linux/netdevice.h> > >> > #include <linux/spinlock.h> > >> > #include <linux/refcount.h> > >> >+#include <linux/usb.h> > >> > #include <linux/workqueue.h> > >> > #include <linux/u64_stats_sync.h> > >> > #include <linux/timekeeping.h> > >> >@@ -6685,12 +6686,37 @@ int devlink_info_version_running_put_ext(struct devlink_info_req *req, > >> > } > >> > EXPORT_SYMBOL_GPL(devlink_info_version_running_put_ext); > >> > > >> >+static int devlink_nl_driver_info_get(struct device_driver *drv, > >> >+ struct devlink_info_req *req) > >> >+{ > >> >+ if (!drv) > >> >+ return 0; > >> >+ > >> >+ if (drv->name[0]) > >> >+ return devlink_info_driver_name_put(req, drv->name); > >> > >> Make sure that this provides the same value for all existing drivers > >> using devlink. > > > >There are 21 drivers so far which reports the driver name through devlink. c.f.: > > $ git grep "devlink_info_driver_name_put(" drivers | wc -l > > > >Out of those 21, there is only one: the mlxsw which seems to report > >something different than device_driver::name. Instead it reports some > >bus_info: > > https://elixir.bootlin.com/linux/v6.1-rc1/source/drivers/net/ethernet/mellanox/mlxsw/core.c#L1462 > > https://elixir.bootlin.com/linux/v6.1-rc1/source/drivers/net/ethernet/mellanox/mlxsw/core.h#L504 > > > >I am not sure what the bus_info is here, but it looks like a misuse of > >the field here. > > When you are not sure, look into the code to find out :) I see no misue. > What exactly do you mean by that?
I mean that device_kind, it does not sound like a field that would hold the driver name.
Looking deeper in the code, I got the confirmation. bus_info::device_kind is initialized here (among other): https://elixir.bootlin.com/linux/v6.1-rc1/source/drivers/net/ethernet/mellanox/mlxsw/i2c.c#L714
and it uses ic2_client::name which indicate the type of the device (e.g. chip name): https://elixir.bootlin.com/linux/v6.1-rc1/source/include/linux/i2c.h#L317
So I confirm that this is a misuse. This driver does not report the driver's name.
> >> >+ > >> >+ return 0; > >> >+} > >> >+ > >> >+static int devlink_nl_usb_info_get(struct usb_device *udev, > >> >+ struct devlink_info_req *req) > >> >+{ > >> >+ if (!udev) > >> >+ return 0; > >> >+ > >> >+ if (udev->serial[0]) > >> >+ return devlink_info_serial_number_put(req, udev->serial); > >> >+ > >> >+ return 0; > >> >+} > >> >+ > >> > static int > >> > devlink_nl_info_fill(struct sk_buff *msg, struct devlink *devlink, > >> > enum devlink_command cmd, u32 portid, > >> > u32 seq, int flags, struct netlink_ext_ack *extack) > >> > { > >> > struct devlink_info_req req = {}; > >> >+ struct device *dev = devlink_to_dev(devlink); > >> > void *hdr; > >> > int err; > >> > > >> >@@ -6707,6 +6733,16 @@ devlink_nl_info_fill(struct sk_buff *msg, struct devlink *devlink, > >> > if (err) > >> > goto err_cancel_msg; > >> > > >> >+ err = devlink_nl_driver_info_get(dev->driver, &req); > >> >+ if (err) > >> >+ goto err_cancel_msg; > >> >+ > >> >+ if (!strcmp(dev->parent->type->name, "usb_device")) { > >> > >> Comparing to string does not seem correct here. > > > >There is a is_usb_device() which does the check: > > https://elixir.bootlin.com/linux/v6.1-rc1/source/drivers/usb/core/usb.h#L152 > > > >but this macro is not exposed outside of the usb core. The string > >comparison was the only solution I found. > > Find a different one. String check here is wrong. > > > >Do you have any other ideas? If not and if this goes further than the > >RFC stage, I will ask the USB folks if there is a better way. > > > >> > >> >+ err = devlink_nl_usb_info_get(to_usb_device(dev->parent), &req); > >> > >> As Jakub pointed out, you have to make sure that driver does not put the > >> same attrs again. You have to introduce this functionality with removing > >> the fill-ups in drivers atomically, in a single patch. > > > >Either this, either track if the attribute is already set. I would > >prefer to remove all drivers fill-ups but this is not feasible for the > >serial number. c.f. my reply to Jacub in this thread: > > https://lore.kernel.org/netdev/CAMZ6RqJ8_=h1SS7WmBeEB=75wsvVUZrb-8ELCDtpZb0gSs=2+A@mail.gmail.com/ > > Sure, but for the driver name it is. Let's start there.
I will do a first patch only for the driver name and think again of the USB serial later on.
Yours sincerely, Vincent Mailhol
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