Nilay Shroff 6e51a1279c block: acquire q->limits_lock while reading sysfs attributes
There're few sysfs attributes(RW) whose store method is protected
with q->limits_lock, however the corresponding show method of these
attributes run holding q->sysfs_lock and that doesn't make sense
as ideally the show method of these attributes should also run
holding q->limits_lock instead of q->sysfs_lock. Hence update the
show method of these sysfs attributes so that reading of these
attributes acquire q->limits_lock instead of q->sysfs_lock.

Similarly, there're few sysfs attributes(RO) whose show method is
currently protected with q->sysfs_lock however updates to these
attributes could occur using atomic limit update APIs such as queue_
limits_start_update() and queue_limits_commit_update() which run
holding q->limits_lock. So that means that reading these attributes
holding q->sysfs_lock doesn't make sense. Hence update the show method
of these sysfs attributes(RO) such that they run with holding q->
limits_lock instead of q->sysfs_lock.

We have defined a new macro QUEUE_LIM_RO_ENTRY() which uses new ->show_
limit() method and it runs holding q->limits_lock. All existing sysfs
attributes(RO) which needs protection using q->limits_lock while
reading have been now updated to use this new macro for initialization.

Also, the existing QUEUE_LIM_RW_ENTRY() is updated to use new ->show_
limit() method for reading attributes instead of existing ->show()
method. As ->show_limit() runs holding q->limits_lock, the existing
sysfs attributes(RW) requiring protection are now inherently protected
using q->limits_lock instead of q->sysfs_lock.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250304102551.2533767-2-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2025-03-10 07:30:18 -06:00
2024-09-01 20:43:24 -07:00
2025-02-04 11:27:45 -05:00
2022-09-28 09:02:20 +02:00
2025-02-09 12:45:03 -08:00
2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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