[PATCH v3 0/2] uio_hv_generic: Fix ring buffer sysfs creation path
From: Naman Jain
Date: Fri Mar 28 2025 - 01:28:02 EST
Hi,
PFB change logs:
Changes since v2:
https://lore.kernel.org/all/20250318061558.3294-1-namjain@xxxxxxxxxxxxxxxxxxx/
Addressed Greg's comments:
* Split the original patch into two.
* Updated the commit message to explain the problem scenario.
* Added comments for new APIs in the kerneldoc format.
* Highlighted potential race conditions and explained why sysfs should not be created in the
driver probe.
* Made minor changes to how the sysfs_update_group return value is handled.
Changes since v1:
https://lore.kernel.org/all/20250225052001.2225-1-namjain@xxxxxxxxxxxxxxxxxxx/
* Fixed race condition in setting channel->mmap_ring_buffer by
introducing a new variable for visibility of sysfs (addressed Greg's
comments)
* Used binary attribute fields instead of regular ones for initializing attribute_group.
* Make size of ring sysfs dynamic based on actual ring buffer's size.
* Preferred to keep mmap function in uio_hv_generic to give more control over ring's
mmap functionality, since this is specific to uio_hv_generic driver.
* Remove spurious warning during sysfs creation in uio_hv_generic probe.
* Added comments in a couple of places.
Changes since RFC patch:
https://lore.kernel.org/all/20250214064351.8994-1-namjain@xxxxxxxxxxxxxxxxxxx/
* Different approach to solve the problem is proposed (credits to
Michael Kelley).
* Core logic for sysfs creation moved out of uio_hv_generic, to VMBus
drivers where rest of the sysfs attributes for a VMBus channel
are defined. (addressed Greg's comments)
* Used attribute groups instead of sysfs_create* functions, and bundled
ring attribute with other attributes for the channel sysfs.
Error logs:
[ 35.574120] ------------[ cut here ]------------
[ 35.574122] WARNING: CPU: 0 PID: 10 at fs/sysfs/file.c:591 sysfs_create_bin_file+0x81/0x90
[ 35.574168] Workqueue: hv_pri_chan vmbus_add_channel_work
[ 35.574172] RIP: 0010:sysfs_create_bin_file+0x81/0x90
[ 35.574197] Call Trace:
[ 35.574199] <TASK>
[ 35.574200] ? show_regs+0x69/0x80
[ 35.574217] ? __warn+0x8d/0x130
[ 35.574220] ? sysfs_create_bin_file+0x81/0x90
[ 35.574222] ? report_bug+0x182/0x190
[ 35.574225] ? handle_bug+0x5b/0x90
[ 35.574244] ? exc_invalid_op+0x19/0x70
[ 35.574247] ? asm_exc_invalid_op+0x1b/0x20
[ 35.574252] ? sysfs_create_bin_file+0x81/0x90
[ 35.574255] hv_uio_probe+0x1e7/0x410 [uio_hv_generic]
[ 35.574271] vmbus_probe+0x3b/0x90
[ 35.574275] really_probe+0xf4/0x3b0
[ 35.574279] __driver_probe_device+0x8a/0x170
[ 35.574282] driver_probe_device+0x23/0xc0
[ 35.574285] __device_attach_driver+0xb5/0x140
[ 35.574288] ? __pfx___device_attach_driver+0x10/0x10
[ 35.574291] bus_for_each_drv+0x86/0xe0
[ 35.574294] __device_attach+0xc1/0x200
[ 35.574297] device_initial_probe+0x13/0x20
[ 35.574315] bus_probe_device+0x99/0xa0
[ 35.574318] device_add+0x647/0x870
[ 35.574320] ? hrtimer_init+0x28/0x70
[ 35.574323] device_register+0x1b/0x30
[ 35.574326] vmbus_device_register+0x83/0x130
[ 35.574328] vmbus_add_channel_work+0x135/0x1a0
[ 35.574331] process_one_work+0x177/0x340
[ 35.574348] worker_thread+0x2b2/0x3c0
[ 35.574350] kthread+0xe3/0x1f0
[ 35.574353] ? __pfx_worker_thread+0x10/0x10
[ 35.574356] ? __pfx_kthread+0x10/0x10
Regards,
Naman
Naman Jain (2):
uio_hv_generic: Fix sysfs creation path for ring buffer
Drivers: hv: Make the sysfs node size for the ring buffer dynamic
drivers/hv/hyperv_vmbus.h | 6 ++
drivers/hv/vmbus_drv.c | 119 ++++++++++++++++++++++++++++++++++-
drivers/uio/uio_hv_generic.c | 33 ++++------
include/linux/hyperv.h | 6 ++
4 files changed, 143 insertions(+), 21 deletions(-)
base-commit: db8da9da41bced445077925f8a886c776a47440c
--
2.34.1