It is a useful helper hence move it to common code so others can enjoy
it.
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Pull modules updates from Jessica Yu:
"Summary of modules changes for the 5.11 merge window:
- Fix a race condition between systemd/udev and the module loader.
The module loader was sending a uevent before the module was fully
initialized (i.e., before its init function has been called). This
means udev can start processing the module uevent before the module
has finished initializing, and some udev rules expect that the
module has initialized already upon receiving the uevent.
This resulted in some systemd mount units failing if udev processes
the event faster than the module can finish init. This is fixed by
delaying the uevent until after the module has called its init
routine.
- Make the linker array sections for kernel params and module version
attributes more robust by switching to use the alignment of the
type in question.
Namely, linker section arrays will be constructed using the
alignment required by the struct (using __alignof__()) as opposed
to a specific value such as sizeof(void *) or sizeof(long). This is
less likely to cause breakages should the size of the type ever
change (Johan Hovold)
- Fix module state inconsistency by setting it back to GOING when a
module fails to load and is on its way out (Miroslav Benes)
- Some comment and code cleanups (Sergey Shtylyov)"
* tag 'modules-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
module: delay kobject uevent until after module init call
module: drop semicolon from version macro
init: use type alignment for kernel parameters
params: clean up module-param macros
params: use type alignment for kernel parameters
params: drop redundant "unused" attributes
module: simplify version-attribute handling
module: drop version-attribute alignment
module: fix comment style
module: add more 'kernel-doc' comments
module: fix up 'kernel-doc' comments
module: only handle errors with the *switch* statement in module_sig_check()
module: avoid *goto*s in module_sig_check()
module: merge repetitive strings in module_sig_check()
module: set MODULE_STATE_GOING state when a module fails to load
Instead of using the array-of-pointers trick to avoid having gcc mess up
the built-in module-version array stride, specify type alignment when
declaring entries to prevent gcc from increasing alignment.
This is essentially an alternative (one-line) fix to the problem
addressed by commit b4bc842802 ("module: deal with alignment issues in
built-in module versions").
gcc can increase the alignment of larger objects with static extent as
an optimisation, but this can be suppressed by using the aligned
attribute when declaring variables.
Note that we have been relying on this behaviour for kernel parameters
for 16 years and it indeed hasn't changed since the introduction of the
aligned attribute in gcc-3.1.
Link: https://lore.kernel.org/lkml/20201103175711.10731-1-johan@kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1334 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Function param_attr_show could overflow the buffer it is operating on.
The buffer size is PAGE_SIZE, and the string returned by
attribute->param->ops->get is generated by scnprintf(buffer, PAGE_SIZE,
...) so it could be PAGE_SIZE - 1 long, with the terminating '\0' at the
very end of the buffer. Calling strcat(..., "\n") on this isn't safe, as
the '\0' will be replaced by '\n' (OK) and then another '\0' will be added
past the end of the buffer (not OK.)
Simply add the trailing '\n' when writing the attribute contents to the
buffer originally. This is safe, and also faster.
Credits to Teradata for discovering this issue.
Link: http://lkml.kernel.org/r/20170928162602.60c379c7@endymion
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull module updates from Rusty Russell:
"Nothing exciting, minor tweaks and cleanups"
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
scripts: [modpost] add new sections to white list
modpost: Add flag -E for making section mismatches fatal
params: don't ignore the rest of cmdline if parse_one() fails
modpost: abort if a module symbol is too long
parse_args() just aborts after it hits an error, so other args
at the same initcall level are simply ignored. This can lead to
other hard-to-understand problems, for example my testing machine
panics during the boot if I pass "locktorture.verbose=true".
Change parse_args() to save the err code for return and continue.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Pull module updates from Rusty Russell:
"Main excitement here is Peter Zijlstra's lockless rbtree optimization
to speed module address lookup. He found some abusers of the module
lock doing that too.
A little bit of parameter work here too; including Dan Streetman's
breaking up the big param mutex so writing a parameter can load
another module (yeah, really). Unfortunately that broke the usual
suspects, !CONFIG_MODULES and !CONFIG_SYSFS, so those fixes were
appended too"
* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (26 commits)
modules: only use mod->param_lock if CONFIG_MODULES
param: fix module param locks when !CONFIG_SYSFS.
rcu: merge fix for Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
module: add per-module param_lock
module: make perm const
params: suppress unused variable error, warn once just in case code changes.
modules: clarify CONFIG_MODULE_COMPRESS help, suggest 'N'.
kernel/module.c: avoid ifdefs for sig_enforce declaration
kernel/workqueue.c: remove ifdefs over wq_power_efficient
kernel/params.c: export param_ops_bool_enable_only
kernel/params.c: generalize bool_enable_only
kernel/module.c: use generic module param operaters for sig_enforce
kernel/params: constify struct kernel_param_ops uses
sysfs: tightened sysfs permission checks
module: Rework module_addr_{min,max}
module: Use __module_address() for module_address_lookup()
module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING
module: Optimize __module_address() using a latched RB-tree
rbtree: Implement generic latch_tree
seqlock: Introduce raw_read_seqcount_latch()
...
As Dan Streetman points out, the entire point of locking for is to
stop sysfs accesses, so they're elided entirely in the !SYSFS case.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Add a "param_lock" mutex to each module, and update params.c to use
the correct built-in or module mutex while locking kernel params.
Remove the kparam_block_sysfs_r/w() macros, replace them with direct
calls to kernel_param_[un]lock(module).
The kernel param code currently uses a single mutex to protect
modification of any and all kernel params. While this generally works,
there is one specific problem with it; a module callback function
cannot safely load another module, i.e. with request_module() or even
with indirect calls such as crypto_has_alg(). If the module to be
loaded has any of its params configured (e.g. with a /etc/modprobe.d/*
config file), then the attempt will result in a deadlock between the
first module param callback waiting for modprobe, and modprobe trying to
lock the single kernel param mutex to set the new module's param.
This fixes that by using per-module mutexes, so that each individual module
is protected against concurrent changes in its own kernel params, but is
not blocked by changes to other module params. All built-in modules
continue to use the built-in mutex, since they will always be loaded at
runtime and references (e.g. request_module(), crypto_has_alg()) to them
will never cause load-time param changing.
This also simplifies the interface used by modules to block sysfs access
to their params; while there are currently functions to block and unblock
sysfs param access which are split up by read and write and expect a single
kernel param to be passed, their actual operation is identical and applies
to all params, not just the one passed to them; they simply lock and unlock
the global param mutex. They are replaced with direct calls to
kernel_param_[un]lock(THIS_MODULE), which locks THIS_MODULE's param_lock, or
if the module is built-in, it locks the built-in mutex.
Suggested-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Change the struct kernel_param.perm field to a const, as it should never
be changed.
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cut from larger patch)
It shouldn't fail due to OOM (it's boot time), and already warns if we
get two identical names. But you never know what the future holds, and
WARN_ON_ONCE() keeps gcc happy with minimal code.
Reported-by: Louis Langholtz <lou_langholtz@me.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
