-
Ira Weiny authoredkmap() and kmap_atomic() are being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. kmap_local_page() is safe from any context and is therefore redundant with kmap_atomic() with the exception of any pagefault or preemption disable requirements. However, using kmap_atomic() for these side effects makes the code less clear. So any requirement for pagefault or preemption disable should be made explicitly. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored. Link: https://lkml.kernel.org/r/20220813220034.806698-1-ira.weiny@intel.com Signed-off-by:
Ira Weiny <ira.weiny@intel.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>Ira Weiny authoredkmap() and kmap_atomic() are being deprecated in favor of kmap_local_page(). There are two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) it also requires global TLB invalidation when the kmap's pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. kmap_local_page() is safe from any context and is therefore redundant with kmap_atomic() with the exception of any pagefault or preemption disable requirements. However, using kmap_atomic() for these side effects makes the code less clear. So any requirement for pagefault or preemption disable should be made explicitly. With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, the tasks can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored. Link: https://lkml.kernel.org/r/20220813220034.806698-1-ira.weiny@intel.com Signed-off-by:
Ira Weiny <ira.weiny@intel.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
checkpatch.pl 225.75 KiB
#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0
#
# (c) 2001, Dave Jones. (the file handling bit)
# (c) 2005, Joel Schopp <jschopp@austin.ibm.com> (the ugly bit)
# (c) 2007,2008, Andy Whitcroft <apw@uk.ibm.com> (new conditions, test suite)
# (c) 2008-2010 Andy Whitcroft <apw@canonical.com>
# (c) 2010-2018 Joe Perches <joe@perches.com>
use strict;
use warnings;
use POSIX;
use File::Basename;
use Cwd 'abs_path';
use Term::ANSIColor qw(:constants);
use Encode qw(decode encode);
my $P = $0;
my $D = dirname(abs_path($P));
my $V = '0.32';
use Getopt::Long qw(:config no_auto_abbrev);
my $quiet = 0;
my $verbose = 0;
my %verbose_messages = ();
my %verbose_emitted = ();
my $tree = 1;
my $chk_signoff = 1;
my $chk_patch = 1;
my $tst_only;
my $emacs = 0;
my $terse = 0;
my $showfile = 0;
my $file = 0;
my $git = 0;
my %git_commits = ();
my $check = 0;
my $check_orig = 0;
my $summary = 1;
my $mailback = 0;
my $summary_file = 0;
my $show_types = 0;
my $list_types = 0;
my $fix = 0;
my $fix_inplace = 0;
my $root;
my $gitroot = $ENV{'GIT_DIR'};
$gitroot = ".git" if !defined($gitroot);
my %debug;
my %camelcase = ();
my %use_type = ();
my @use = ();
my %ignore_type = ();
my @ignore = ();
my $help = 0;
my $configuration_file = ".checkpatch.conf";
my $max_line_length = 100;
my $ignore_perl_version = 0;
my $minimum_perl_version = 5.10.0;
my $min_conf_desc_length = 4;
my $spelling_file = "$D/spelling.txt";
my $codespell = 0;
my $codespellfile = "/usr/share/codespell/dictionary.txt";
my $user_codespellfile = "";
my $conststructsfile = "$D/const_structs.checkpatch";
my $docsfile = "$D/../Documentation/dev-tools/checkpatch.rst";
my $typedefsfile;
my $color = "auto";