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From: Michael Walle <michael@walle.cc>
To: saravanak@google.com
Cc: ardb@kernel.org, devicetree@vger.kernel.org,
	frowand.list@gmail.com, gregkh@linuxfoundation.org,
	grygorii.strashko@ti.com, kernel-team@android.com,
	laurent.pinchart@ideasonboard.com, lenb@kernel.org,
	linux-acpi@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-kernel@vger.kernel.org, maz@kernel.org, rafael@kernel.org,
	rjw@rjwysocki.net, robh+dt@kernel.org, tglx@linutronix.de,
	tomi.valkeinen@ti.com, Michael Walle <michael@walle.cc>
Subject: Re: [PATCH v2 16/17] driver core: Refactor fw_devlink feature
Date: Tue, 29 Dec 2020 04:34:40 +0100
Message-ID: <20201229033440.32142-1-michael@walle.cc> (raw)
In-Reply-To: <20201121020232.908850-17-saravanak@google.com>

> The current implementation of fw_devlink is very inefficient because it
> tries to get away without creating fwnode links in the name of saving
> memory usage. Past attempts to optimize runtime at the cost of memory
> usage were blocked with request for data showing that the optimization
> made significant improvement for real world scenarios.
> 
> We have those scenarios now. There have been several reports of boot
> time increase in the order of seconds in this thread [1]. Several OEMs
> and SoC manufacturers have also privately reported significant
> (350-400ms) increase in boot time due to all the parsing done by
> fw_devlink.
> 
> So this patch uses all the setup done by the previous patches in this
> series to refactor fw_devlink to be more efficient. Most of the code has
> been moved out of firmware specific (DT mostly) code into driver core.
> 
> This brings the following benefits:
> - Instead of parsing the device tree multiple times during bootup,
>   fw_devlink parses each fwnode node/property only once and creates
>   fwnode links. The rest of the fw_devlink code then just looks at these
>   fwnode links to do rest of the work.
> 
> - Makes it much easier to debug probe issue due to fw_devlink in the
>   future. fw_devlink=on blocks the probing of devices if they depend on
>   a device that hasn't been added yet. With this refactor, it'll be very
>   easy to tell what that device is because we now have a reference to
>   the fwnode of the device.
> 
> - Much easier to add fw_devlink support to ACPI and other firmware
>   types. A refactor to move the common bits from DT specific code to
>   driver core was in my TODO list as a prerequisite to adding ACPI
>   support to fw_devlink. This series gets that done.
> 
> [1] - https://lore.kernel.org/linux-omap/ea02f57e-871d-cd16-4418-c1da4bbc4696@ti.com/
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Tested-by: Grygorii Strashko <grygorii.strashko@ti.com>

git bisect show that this commit broke my board in 5.11-rc1:

[    2.294375] sysfs: cannot create duplicate filename '/devices/virtual/devlink/0000:00:00.1--0000:00:00.1'
[    2.303999] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.11.0-rc1-00016-ga0fb284b267 #267
[    2.312125] Hardware name: Kontron SMARC-sAL28 (4 Lane) (DT)
[    2.317804] Call trace:
[    2.320253]  dump_backtrace+0x0/0x1b8
[    2.323936]  show_stack+0x20/0x70
[    2.327263]  dump_stack+0xd8/0x134
[    2.330677]  sysfs_warn_dup+0x6c/0x88
[    2.334351]  sysfs_create_dir_ns+0xe8/0x100
[    2.338547]  kobject_add_internal+0x9c/0x290
[    2.342833]  kobject_add+0xa0/0x108
[    2.346331]  device_add+0xfc/0x798
[    2.349746]  device_link_add+0x454/0x5e0
[    2.353682]  fw_devlink_create_devlink+0xb8/0xc8
[    2.358316]  __fw_devlink_link_to_suppliers+0x84/0x180
[    2.363474]  __fw_devlink_link_to_suppliers+0x134/0x180
[    2.368718]  device_add+0x778/0x798
[    2.372217]  device_register+0x28/0x38
[    2.375979]  __mdiobus_register+0x94/0x340
[    2.380089]  of_mdiobus_register+0xb4/0x380
[    2.384285]  enetc_pf_probe+0x73c/0xb10
[    2.388132]  local_pci_probe+0x48/0xb8
[    2.391896]  pci_device_probe+0x120/0x1c0
[    2.395920]  really_probe+0xec/0x3c0
[    2.399505]  driver_probe_device+0x60/0xc0
[    2.403614]  device_driver_attach+0x7c/0x88
[    2.407810]  __driver_attach+0x60/0xe8
[    2.411570]  bus_for_each_dev+0x7c/0xd0
[    2.415419]  driver_attach+0x2c/0x38
[    2.419004]  bus_add_driver+0x194/0x1f8
[    2.422851]  driver_register+0x6c/0x128
[    2.426698]  __pci_register_driver+0x4c/0x58
[    2.430983]  enetc_pf_driver_init+0x2c/0x38
[    2.435181]  do_one_initcall+0x54/0x2d8
[    2.439029]  kernel_init_freeable+0x1fc/0x268
[    2.443403]  kernel_init+0x1c/0x120
[    2.446904]  ret_from_fork+0x10/0x30
[    2.450502] kobject_add_internal failed for 0000:00:00.1--0000:00:00.1 with -EEXIST, don't try to register things with the same name in the same directory.

Looks like it will generate that link twice? Let me know if I can help
testing.

See also: https://lavalab.kontron.com/scheduler/job/3894#L831

-michael

  parent reply index

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-21  2:02 [PATCH v2 00/17] Refactor fw_devlink to significantly improve boot time Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 01/17] Revert "driver core: Avoid deferred probe due to fw_devlink_pause/resume()" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 02/17] Revert "driver core: Rename dev_links_info.defer_sync to defer_hook" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 03/17] Revert "driver core: Don't do deferred probe in parallel with kernel_init thread" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 04/17] Revert "driver core: Remove check in driver_deferred_probe_force_trigger()" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 05/17] Revert "of: platform: Batch fwnode parsing when adding all top level devices" Saravana Kannan
2020-12-07 22:18   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 06/17] Revert "driver core: fw_devlink: Add support for batching fwnode parsing" Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 07/17] driver core: Add fwnode_init() Saravana Kannan
2020-12-06  7:26   ` Leon Romanovsky
2020-12-07 19:25     ` Saravana Kannan
2020-12-07 19:53       ` Leon Romanovsky
2020-12-07 20:36         ` Saravana Kannan
2020-12-08  6:34           ` Leon Romanovsky
2020-12-07 22:20   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 08/17] driver core: Add fwnode link support Saravana Kannan
2020-12-06  7:48   ` Leon Romanovsky
2020-12-07 19:25     ` Saravana Kannan
2020-12-07 19:56       ` Leon Romanovsky
2020-12-07 22:21   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 09/17] driver core: Allow only unprobed consumers for SYNC_STATE_ONLY device links Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 10/17] device property: Add fwnode_is_ancestor_of() and fwnode_get_next_parent_dev() Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 11/17] driver core: Redefine the meaning of fwnode_operations.add_links() Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 12/17] driver core: Add fw_devlink_parse_fwtree() Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 13/17] driver core: Use device's fwnode to check if it is waiting for suppliers Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 14/17] of: property: Update implementation of add_links() to create fwnode links Saravana Kannan
2020-12-07 22:37   ` Rob Herring
2020-11-21  2:02 ` [PATCH v2 15/17] efi: " Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 16/17] driver core: Refactor fw_devlink feature Saravana Kannan
2020-11-23 16:00   ` [driver core] 95f755a4ef: will-it-scale.per_process_ops 2.2% improvement kernel test robot
2020-12-11 14:11   ` [PATCH v2 16/17] driver core: Refactor fw_devlink feature Qian Cai
2020-12-11 16:34     ` Robin Murphy
2020-12-11 17:51       ` Saravana Kannan
2020-12-11 18:03         ` Marc Zyngier
2020-12-11 18:20           ` Saravana Kannan
2020-12-11 19:07             ` Marc Zyngier
2020-12-11 22:29               ` Saravana Kannan
2020-12-29  3:34   ` Michael Walle [this message]
2021-01-05 19:00     ` Saravana Kannan
2021-01-05 21:03       ` Michael Walle
2021-01-06 23:29         ` Saravana Kannan
2020-11-21  2:02 ` [PATCH v2 17/17] driver core: Delete pointless parameter in fwnode_operations.add_links Saravana Kannan
2020-12-07 22:38   ` Rob Herring
2020-11-24  8:29 ` [PATCH v2 00/17] Refactor fw_devlink to significantly improve boot time Tomi Valkeinen
2020-11-24 17:25   ` Saravana Kannan
2020-12-03 19:05   ` Saravana Kannan
2020-12-09 18:16 ` Greg Kroah-Hartman
2020-12-09 20:24   ` Saravana Kannan
2020-12-10  9:26     ` Greg Kroah-Hartman

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