diff options
| author | Peter Xu <peterx@redhat.com> | 2020-04-03 18:35:17 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-05-02 08:51:02 +0200 |
| commit | 7cc55e70cbe6bbbbf492805cd0af3c5fc3683cf5 (patch) | |
| tree | a7e32b9d2d400e3d480dd85da2bcdb8dba9c8931 | |
| parent | 45c2e2170b9224eb5a89680ffb57f2d8542d1d2e (diff) | |
sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters
[ Upstream commit 3662daf023500dc084fa3b96f68a6f46179ddc73 ]
The "isolcpus=" parameter allows sub-parameters before the cpulist is
specified, and if the parser detects an unknown sub-parameters the whole
parameter will be ignored.
This design is incompatible with itself when new sub-parameters are added.
An older kernel will not recognize the new sub-parameter and will
invalidate the whole parameter so the CPU isolation will not take
effect. It emits a warning:
isolcpus: Error, unknown flag
The better and compatible way is to allow "isolcpus=" to skip unknown
sub-parameters, so that even if new sub-parameters are added an older
kernel will still be able to behave as usual even if with the new
sub-parameter specified on the command line.
Ideally this should have been there when the first sub-parameter for
"isolcpus=" was introduced.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200403223517.406353-1-peterx@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | kernel/sched/isolation.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 008d6ac2342b..808244f3ddd9 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -149,6 +149,9 @@ __setup("nohz_full=", housekeeping_nohz_full_setup); static int __init housekeeping_isolcpus_setup(char *str) { unsigned int flags = 0; + bool illegal = false; + char *par; + int len; while (isalpha(*str)) { if (!strncmp(str, "nohz,", 5)) { @@ -169,8 +172,22 @@ static int __init housekeeping_isolcpus_setup(char *str) continue; } - pr_warn("isolcpus: Error, unknown flag\n"); - return 0; + /* + * Skip unknown sub-parameter and validate that it is not + * containing an invalid character. + */ + for (par = str, len = 0; *str && *str != ','; str++, len++) { + if (!isalpha(*str) && *str != '_') + illegal = true; + } + + if (illegal) { + pr_warn("isolcpus: Invalid flag %.*s\n", len, par); + return 0; + } + + pr_info("isolcpus: Skipped unknown flag %.*s\n", len, par); + str++; } /* Default behaviour for isolcpus without flags */ |