[PATCH v4 22/58] dyndbg-test: change do_prints testpoint to accept a loopct
From: Jim Cromie <jim.cromie@gmail.com>
Date: 2025-08-03 03:59:07
Also in:
amd-gfx, dri-devel, intel-gfx, linux-arm-msm, lkml
Subsystem:
dynamic debug, library code, the rest · Maintainers:
Jason Baron, Jim Cromie, Andrew Morton, Linus Torvalds
echo 1000 > /sys/module/test_dynamic_debug/parameters/do_prints This allows its use as a scriptable load generator, to generate dynamic-prefix-emits for flag combinations vs undecorated messages. This will make it easy to assess the cost of the prefixing. Reading the ./do_prints node also prints messages (once) to the-log. NB: the count is clamped to 10000, chosen to be notice able, but not annoying, and not enough to accidentally flood the logs. Signed-off-by: Jim Cromie <jim.cromie@gmail.com> --- lib/test_dynamic_debug.c | 37 ++++++++++++++++++++++++++----------- 1 file changed, 26 insertions(+), 11 deletions(-)
diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
index e83b34b6d6b95..8713537363713 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c@@ -29,18 +29,30 @@ #include <linux/module.h> -/* re-gen output by reading or writing sysfs node: do_prints */ - -static void do_prints(void); /* device under test */ +/* re-trigger debug output by reading or writing sysfs node: do_prints */ +#define PRINT_CLAMP 10000 +static void do_prints(unsigned int); /* device under test */ static int param_set_do_prints(const char *instr, const struct kernel_param *kp) { - do_prints(); + int rc; + unsigned int ct; + + rc = kstrtouint(instr, 0, &ct); + if (rc) { + pr_err("expecting numeric input, using 1 instead\n"); + ct = 1; + } + if (ct > PRINT_CLAMP) { + ct = PRINT_CLAMP; + pr_info("clamping print-count to %d\n", ct); + } + do_prints(ct); return 0; } static int param_get_do_prints(char *buffer, const struct kernel_param *kp) { - do_prints(); - return scnprintf(buffer, PAGE_SIZE, "did do_prints\n"); + do_prints(1); + return scnprintf(buffer, PAGE_SIZE, "did 1 do_prints\n"); } static const struct kernel_param_ops param_ops_do_prints = { .set = param_set_do_prints,
@@ -191,17 +203,20 @@ static void do_levels(void) prdbg(V7); } -static void do_prints(void) +static void do_prints(unsigned int ct) { - pr_debug("do_prints:\n"); - do_cats(); - do_levels(); + /* maybe clamp this */ + pr_debug("do-prints %d times:\n", ct); + for (; ct; ct--) { + do_cats(); + do_levels(); + } } static int __init test_dynamic_debug_init(void) { pr_debug("init start\n"); - do_prints(); + do_prints(1); pr_debug("init done\n"); return 0; }
--
2.50.1