[igt-dev] [PATCH i-g-t v3 1/1] lib/core: Use whitelist with kmsg filter

[Petri Latvala]

dmesg messages of level >=warn don't result in an IGT_LOG_WARN if they
match a whitelist regexp now.

The whitelist is not configureable without rebuilding, and it's not
even possible to use a different whitelist for different drivers;
launching the kmsg monitor happens way before opening the driver (if
any).

v2: Use static and a less yelling variable name for the whitelist,
    compare to REG_NOMATCH directly, construct the regexp in a nicer
    looking way (Chris). Be more verbose when monitoring stops.
v3: More patterns, document them.

Signed-off-by: Petri Latvala <petri.latvala at intel.com>
---
 lib/igt_core.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/lib/igt_core.c b/lib/igt_core.c
index 0b3bf49e..6bcf004a 100644
--- a/lib/igt_core.c
+++ b/lib/igt_core.c
@@ -55,6 +55,7 @@
 #include <limits.h>
 #include <locale.h>
 #include <uwildmat/uwildmat.h>
+#include <regex.h>
 #ifdef HAVE_GLIB
 #include <glib.h>
 #endif
@@ -572,6 +573,37 @@ static void oom_adjust_for_doom(void)
 
 }
 
+/*
+ * This regexp controls the kmsg monitor handling. All kernel log
+ * records that have log level of warning or higher get inserted into
+ * IGT log buffer with an IGT_LOG_WARN unless they match this
+ * regexp. Otherwise they get inserted at IGT_LOG_DEBUG.
+ */
+
+#define _ "|"
+static const char igt_dmesg_whitelist[] =
+	"ACPI: button: The lid device is not compliant to SW_LID" _
+	"ACPI: .*: Unable to dock!" _
+	"IRQ [0-9]+: no longer affine to CPU[0-9]+" _
+	"IRQ fixup: irq [0-9]+ move in progress, old vector [0-9]+" _
+	/* i915 tests set module options, expected message */
+	"Setting dangerous option [a-z_]+ - tainting kernel" _
+	/* Raw printk() call, uses default log level (warn) */
+	"Suspending console\\(s\\) \\(use no_console_suspend to debug\\)" _
+	"atkbd serio[0-9]+: Failed to (deactivate|enable) keyboard on isa[0-9]+/serio[0-9]+" _
+	"cache: parent cpu[0-9]+ should not be sleeping" _
+	"hpet[0-9]+: lost [0-9]+ rtc interrupts" _
+	/* i915 selftests terminate normally with ENODEV from the
+	 * module load after the testing finishes, which produces this
+	 * message.
+	 */
+	"i915: probe of [0-9:.]+ failed with error -25" _
+	/* swiotbl warns even when asked not to */
+	"mock: DMA: Out of SW-IOMMU space for [0-9]+ bytes" _
+	"usb usb[0-9]+: root hub lost power or was reset"
+	;
+#undef _
+
 static void *kmsg_capture(void *arg)
 {
 	/*
@@ -584,6 +616,13 @@ static void *kmsg_capture(void *arg)
 	char *line = NULL;
 	size_t line_len = 0;
 	ssize_t read;
+	regex_t re;
+
+	if (regcomp(&re, igt_dmesg_whitelist, REG_EXTENDED | REG_NOSUB) != 0) {
+		igt_warn("Cannot compile dmesg whitelist regexp\n");
+		fclose(kmsg_file);
+		return NULL;
+	}
 
 	while ((read = getline(&line, &line_len, kmsg_file))) {
 		int s;
@@ -604,7 +643,8 @@ static void *kmsg_capture(void *arg)
 			   &seq, &ts_usec, &continuation);
 
 		if (s == 4) {
-			if ((flags & 0x7) <= 4)
+			if ((flags & 0x7) <= 4 &&
+			    regexec(&re, line, (size_t)0, NULL, 0) == REG_NOMATCH)
 				level = IGT_LOG_WARN;
 			else
 				level = IGT_LOG_DEBUG;
@@ -629,7 +669,11 @@ static void *kmsg_capture(void *arg)
 		}
 	}
 
-	igt_warn("ran out of dmesg, this shouldn't happen\n");
+	igt_warn("Ran out of dmesg, this shouldn't happen. Reason: ");
+	if (errno)
+		igt_warn("%s\n", strerror(errno));
+	else
+		igt_warn("EOF\n");
 
 	free(line);
 	fclose(kmsg_file);
-- 
2.14.1