summaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
authorPeter Xu <peterx@redhat.com>2020-04-03 18:35:17 -0400
committerThomas Gleixner <tglx@linutronix.de>2020-04-15 10:38:26 +0200
commit3662daf023500dc084fa3b96f68a6f46179ddc73 (patch)
tree06cf6888d3cf6482dc942ba50d6e6cf44bd4079d /kernel
parent8f3d9f354286745c751374f5f1fcafee6b3f3136 (diff)
downloadlinux-3662daf023500dc084fa3b96f68a6f46179ddc73.tar.gz
linux-3662daf023500dc084fa3b96f68a6f46179ddc73.tar.bz2
linux-3662daf023500dc084fa3b96f68a6f46179ddc73.zip
sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters
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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/isolation.c21
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 */