From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- tools/perf/util/expr.l | 150 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 tools/perf/util/expr.l (limited to 'tools/perf/util/expr.l') diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l new file mode 100644 index 000000000..f16ccff27 --- /dev/null +++ b/tools/perf/util/expr.l @@ -0,0 +1,150 @@ +%option prefix="expr_" +%option reentrant +%option bison-bridge + +%{ +#include +#include "expr.h" +#include "expr-bison.h" +#include + +char *expr_get_text(yyscan_t yyscanner); +YYSTYPE *expr_get_lval(yyscan_t yyscanner); + +static double __value(YYSTYPE *yylval, char *str, int token) +{ + double num; + + errno = 0; + num = strtod(str, NULL); + if (errno) + return EXPR_ERROR; + + yylval->num = num; + return token; +} + +static int value(yyscan_t scanner) +{ + YYSTYPE *yylval = expr_get_lval(scanner); + char *text = expr_get_text(scanner); + + return __value(yylval, text, NUMBER); +} + +/* + * Allow @ instead of / to be able to specify pmu/event/ without + * conflicts with normal division. + */ +static char *normalize(char *str, int runtime) +{ + char *ret = str; + char *dst = str; + + while (*str) { + if (*str == '\\') { + *dst++ = *++str; + if (!*str) + break; + } + else if (*str == '?') { + char *paramval; + int i = 0; + int size = asprintf(¶mval, "%d", runtime); + + if (size < 0) + *dst++ = '0'; + else { + while (i < size) + *dst++ = paramval[i++]; + free(paramval); + } + } + else + *dst++ = *str; + str++; + } + + *dst = 0x0; + return ret; +} + +static int str(yyscan_t scanner, int token, int runtime) +{ + YYSTYPE *yylval = expr_get_lval(scanner); + char *text = expr_get_text(scanner); + + yylval->str = normalize(strdup(text), runtime); + if (!yylval->str) + return EXPR_ERROR; + + yylval->str = normalize(yylval->str, runtime); + return token; +} + +static int literal(yyscan_t scanner, const struct expr_scanner_ctx *sctx) +{ + YYSTYPE *yylval = expr_get_lval(scanner); + + yylval->num = expr__get_literal(expr_get_text(scanner), sctx); + if (isnan(yylval->num)) { + if (!sctx->is_test) + return EXPR_ERROR; + yylval->num = 1; + } + return LITERAL; +} + +static int nan_value(yyscan_t scanner) +{ + YYSTYPE *yylval = expr_get_lval(scanner); + + yylval->num = NAN; + return NUMBER; +} +%} + +number ([0-9]+\.?[0-9]*|[0-9]*\.?[0-9]+)(e-?[0-9]+)? + +sch [-,=] +spec \\{sch} +sym [0-9a-zA-Z_\.:@?]+ +symbol ({spec}|{sym})+ +literal #[0-9a-zA-Z_\.\-]+ + +%% + struct expr_scanner_ctx *sctx = expr_get_extra(yyscanner); + +d_ratio { return D_RATIO; } +max { return MAX; } +min { return MIN; } +if { return IF; } +else { return ELSE; } +source_count { return SOURCE_COUNT; } +aggr_nr { return AGGR_NR; } +has_event { return HAS_EVENT; } +strcmp_cpuid_str { return STRCMP_CPUID_STR; } +NaN { return nan_value(yyscanner); } +{literal} { return literal(yyscanner, sctx); } +{number} { return value(yyscanner); } +{symbol} { return str(yyscanner, ID, sctx->runtime); } +"|" { return '|'; } +"^" { return '^'; } +"&" { return '&'; } +"<" { return '<'; } +">" { return '>'; } +"-" { return '-'; } +"+" { return '+'; } +"*" { return '*'; } +"/" { return '/'; } +"%" { return '%'; } +"(" { return '('; } +")" { return ')'; } +"," { return ','; } +. { } +%% + +int expr_wrap(void *scanner __maybe_unused) +{ + return 1; +} -- cgit v1.3.1