Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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Rename struct gendisk zone_wplugs_lock field to zone_wplugs_hash_lock to
clearly indicates that this is the spinlock used for manipulating the
hash table of zone write plugs.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The helper function disk_zone_is_full() is only used in
disk_zone_wplug_is_full(). So remove it and open code it directly in
this single caller.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
disk_get_and_lock_zone_wplug() always returns a zone write plug with the
plug lock held. This is unnecessary since this function does not look at
the fields of existing plugs, and new plugs need to be locked only after
their insertion in the disk hash table, when they are being used.
Remove the zone write plug locking from disk_get_and_lock_zone_wplug()
and rename this function disk_get_or_alloc_zone_wplug().
blk_zone_wplug_handle_write() is modified to add locking of the zone
write plug after calling disk_get_or_alloc_zone_wplug() and before
starting to use the plug. This change also simplifies
blk_revalidate_seq_zone() as unlocking the plug becomes unnecessary.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The function disk_zone_wplug_schedule_bio_work() always takes a
reference on the zone write plug of the BIO work being scheduled. This
ensures that the zone write plug cannot be freed while the BIO work is
being scheduled but has not run yet. However, this unconditional
reference taking is fragile since the reference taken is released by the
BIO work blk_zone_wplug_bio_work() function, which implies that there
always must be a 1:1 relation between the work being scheduled and the
work running.
Make sure to drop the reference taken when scheduling the BIO work if
the work is already scheduled, that is, when queue_work() returns false.
Fixes: 9e78c38ab30b ("block: Hold a reference on zone write plugs to schedule submission")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Commit 7b295187287e ("block: Do not remove zone write plugs still in
use") modified disk_should_remove_zone_wplug() to add a check on the
reference count of a zone write plug to prevent removing zone write
plugs from a disk hash table when the plugs are still being referenced
by BIOs or requests in-flight. However, this check does not take into
account that a BIO completion may happen right after its submission by
a zone write plug BIO work, and before the zone write plug BIO work
releases the zone write plug reference count. This situation leads to
disk_should_remove_zone_wplug() returning false as in this case the zone
write plug reference count is at least equal to 3. If the BIO that
completes in such manner transitioned the zone to the FULL condition,
the zone write plug for the FULL zone will remain in the disk hash
table.
Furthermore, relying on a particular value of a zone write plug
reference count to set the BLK_ZONE_WPLUG_UNHASHED flag is fragile as
reading the atomic reference count and doing a comparison with some
value is not overall atomic at all.
Address these issues by reworking the reference counting of zone write
plugs so that removing plugs from a disk hash table can be done
directly from disk_put_zone_wplug() when the last reference on a plug
is dropped.
To do so, replace the function disk_remove_zone_wplug() with
disk_mark_zone_wplug_dead(). This new function sets the zone write plug
flag BLK_ZONE_WPLUG_DEAD (which replaces BLK_ZONE_WPLUG_UNHASHED) and
drops the initial reference on the zone write plug taken when the plug
was added to the disk hash table. This function is called either for
zones that are empty or full, or directly in the case of a forced plug
removal (e.g. when the disk hash table is being destroyed on disk
removal). With this change, disk_should_remove_zone_wplug() is also
removed.
disk_put_zone_wplug() is modified to call the function
disk_free_zone_wplug() to remove a zone write plug from a disk hash
table and free the plug structure (with a call_rcu()), when the last
reference on a zone write plug is dropped. disk_free_zone_wplug()
always checks that the BLK_ZONE_WPLUG_DEAD flag is set.
In order to avoid having multiple zone write plugs for the same zone in
the disk hash table, disk_get_and_lock_zone_wplug() checked for the
BLK_ZONE_WPLUG_UNHASHED flag. This check is removed and a check for
the new BLK_ZONE_WPLUG_DEAD flag is added to
blk_zone_wplug_handle_write(). With this change, we continue preventing
adding multiple zone write plugs for the same zone and at the same time
re-inforce checks on the user behavior by failing new incoming write
BIOs targeting a zone that is marked as dead. This case can happen only
if the user erroneously issues write BIOs to zones that are full, or to
zones that are currently being reset or finished.
Fixes: 7b295187287e ("block: Do not remove zone write plugs still in use")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The queue_hw_ctx field in struct request_queue is an array of pointers
to struct blk_mq_hw_ctx. The number of elements in this array is tracked
by the nr_hw_queues field.
The array is allocated in __blk_mq_realloc_hw_ctxs() using
kcalloc_node() with set->nr_hw_queues elements. q->nr_hw_queues is
subsequently updated to set->nr_hw_queues.
When growing the array, the new array is assigned to queue_hw_ctx before
nr_hw_queues is updated. This is safe because nr_hw_queues (the old
smaller count) is used for bounds checking, which is within the new
larger allocation.
When shrinking the array, nr_hw_queues is updated to the smaller value,
while queue_hw_ctx retains the larger allocation. This is also safe as
the count is within the allocation bounds.
Annotating queue_hw_ctx with __counted_by_ptr(nr_hw_queues) allows the
compiler (with kSAN) to verify that accesses to queue_hw_ctx are within
the valid range defined by nr_hw_queues.
This patch was generated by CodeMender and reviewed by Bill Wendling.
Tested by running blktests.
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Bill Wendling <morbo@google.com>
[axboe: massage commit message]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This adds a function for retrieving the set of Locking objects enabled
for Single User Mode (SUM) and the value of the
RangeStartRangeLengthPolicy parameter.
It retrieves data from the LockingInfo table, specifically the
columns SingleUserModeRanges and RangeStartLengthPolicy, which
were added according to the TCG Opal Feature Set: Single User Mode,
as described in chapters 4.4.3.1 and 4.4.3.2.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Change the column parameter in response_get_column() from u8 to u64
to support the full range of column identifiers.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This ioctl is used to set up RLE (read lock enabled) and WLE (write
lock enabled) parameters of the Locking object.
In Single User Mode (SUM), if the RangeStartRangeLengthPolicy parameter
is set in the 'Reactivate' method, only Admin authority maintains the
locking range length and start (offset) attributes of Locking objects
set up for SUM. All other attributes from struct opal_user_lr_setup
(RLE - read locking enabled, WLE - write locking enabled) shall
remain in possession of the User authority associated with the Locking
object set for SUM.
With the IOC_OPAL_ENABLE_DISABLE_LR ioctl, the opal_user_lr_setup
members 'range_start' and 'range_length' of the ioctl argument are
ignored.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This ioctl is used to set up locking range start (offset)
and locking range length attributes only.
In Single User Mode (SUM), if the RangeStartRangeLengthPolicy parameter
is set in the 'Reactivate' method, only Admin authority maintains the
locking range length and start (offset) attributes of Locking objects
set up for SUM. All other attributes from struct opal_user_lr_setup
(RLE - read locking enabled, WLE - write locking enabled) shall
remain in possession of the User authority associated with the Locking
object set for SUM.
Therefore, we need a separate function for setting up locking range
start and locking range length because it may require two different
authorities (and sessions) if the RangeStartRangeLengthPolicy attribute
is set.
With the IOC_OPAL_LR_SET_START_LEN ioctl, the opal_user_lr_setup
members 'RLE' and 'WLE' of the ioctl argument are ignored.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
IOC_OPAL_LR_SETUP is used to set up a locking range entirely under a
single authority (usually Admin1), but for Single User Mode (SUM),
the permissions for attributes (RangeStart, RangeLength)
and (ReadLockEnable, WriteLockEnable, ReadLocked, WriteLocked)
may be split between two different authorities. Typically, it is Admin1
for the former and the User associated with the LockingRange in SUM
for the latter.
This commit only splits the internals in preparation for the introduction
of separate ioctls for setting RangeStart, RangeLength and the rest
using new ioctl calls.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This adds the 'Reactivate' method as described in the
"TCG Storage Opal SSC Feature Set: Single User Mode"
document (ch. 3.1.1.1).
The method enables switching an already active SED OPAL2 device,
with appropriate firmware support for Single User Mode (SUM),
to or from SUM.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
As desribed in ch. 3.1.1.1.1.3 of TCG Storage Opal SSC Feature Set:
Single User Mode document.
To be used later in Reactivate method implementation.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
As desribed in ch. 3.1.1.1.1.2 of TCG Storage Opal SSC Feature Set:
Single User Mode document.
To be used later in Reactivate method implementation and in function
for retrieving SUM device status.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
As described in ch. 6.3, Table 240 in TCG Storage
Architecture Core Specification document.
It's also referenced in TCG Storage Opal SSC Feature Set:
Single User Mode document, ch. 3.1.1.1 Reactivate method.
It will be used later in Reactivate method implemetation
for sed-opal interface.
Signed-off-by: Ondrej Kozina <okozina@redhat.com>
Reviewed-and-tested-by: Milan Broz <gmazyland@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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