[PATCH] pm_rps: Improve file I/O and restore utilities

[jeff.mcgee@xxxxxxxxx]

From: Jeff McGee <jeff.mcgee@xxxxxxxxx>

Use unbuffered file I/O to simplify and ensure proper sysfs access.
Bionic C library may not re-read a read-only file unless unbuffered,
which results in failure to monitor changes in gt_cur_freq_mhz.

Adapt do_writeval to assert that no write error occurs when we expect
none.

Expand use of restore_assert macro to ensure that original min/max
frequencies are always in place after a test failure.

Signed-off-by: Jeff McGee <jeff.mcgee@xxxxxxxxx>
---
 tests/pm_rps.c | 87 +++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 55 insertions(+), 32 deletions(-)

diff --git a/tests/pm_rps.c b/tests/pm_rps.c
index e8affdb..5223760 100644
--- a/tests/pm_rps.c
+++ b/tests/pm_rps.c
@@ -22,6 +22,7 @@
  *
  * Authors:
  *    Ben Widawsky <ben@xxxxxxxxxxxx>
+ *    Jeff McGee <jeff.mcgee@xxxxxxxxx>
  *
  */
 
@@ -35,14 +36,6 @@
 static bool verbose = false;
 static int origmin, origmax;
 
-#define restore_assert(COND) do { \
-	if (!(COND)) { \
-		writeval(stuff[MIN].filp, origmin); \
-		writeval(stuff[MAX].filp, origmax); \
-		igt_assert(0); \
-	} \
-} while (0);
-
 static const char sysfs_base_path[] = "/sys/class/drm/card%d/gt_%s_freq_mhz";
 enum {
 	CUR,
@@ -66,7 +59,6 @@ static int readval(FILE *filp)
 	int val;
 	int scanned;
 
-	fflush(filp);
 	rewind(filp);
 	scanned = fscanf(filp, "%d", &val);
 	igt_assert(scanned == 1);
@@ -74,32 +66,63 @@ static int readval(FILE *filp)
 	return val;
 }
 
+#define fcur (readval(stuff[CUR].filp))
+#define fmin (readval(stuff[MIN].filp))
+#define fmax (readval(stuff[MAX].filp))
+#define frp0 (readval(stuff[RP0].filp))
+#define frp1 (readval(stuff[RP1].filp))
+#define frpn (readval(stuff[RPn].filp))
+
+static void restore(void)
+{
+	rewind(stuff[MIN].filp);
+	rewind(stuff[MAX].filp);
+
+	if (origmin > fmax) {
+		fprintf(stuff[MAX].filp, "%d", origmax);
+		fprintf(stuff[MIN].filp, "%d", origmin);
+	} else {
+		fprintf(stuff[MIN].filp, "%d", origmin);
+		fprintf(stuff[MAX].filp, "%d", origmax);
+	}
+}
+
+#define restore_assert(COND) do { \
+	if (!(COND)) { \
+		restore(); \
+		igt_assert(0); \
+	} \
+} while (0);
+
 static int do_writeval(FILE *filp, int val, int lerrno)
 {
-	/* Must write twice to sysfs since the first one simply calculates the size and won't return the error */
 	int ret;
+
 	rewind(filp);
 	ret = fprintf(filp, "%d", val);
-	rewind(filp);
-	ret = fprintf(filp, "%d", val);
-	if (ret && lerrno)
-		igt_assert(errno = lerrno);
-	fflush(filp);
+	if (lerrno) {
+		/* Expecting specific error */
+		restore_assert(ret == EOF && errno == lerrno);
+	} else {
+		/* Expecting no error */
+		restore_assert(ret != EOF);
+	}
+
 	return ret;
 }
-#define writeval(filp, val) do_writeval(filp, val, 0)
 
-#define fcur (readval(stuff[CUR].filp))
-#define fmin (readval(stuff[MIN].filp))
-#define fmax (readval(stuff[MAX].filp))
-#define frp0 (readval(stuff[RP0].filp))
-#define frp1 (readval(stuff[RP1].filp))
-#define frpn (readval(stuff[RPn].filp))
+#define writeval(filp, val) do_writeval(filp, val, 0)
+#define writeval_inval(filp, val) do_writeval(filp, val, EINVAL)
 
 static void setfreq(int val)
 {
-	writeval(stuff[MIN].filp, val);
-	writeval(stuff[MAX].filp, val);
+	if (val > fmax) {
+		writeval(stuff[MAX].filp, val);
+		writeval(stuff[MIN].filp, val);
+	} else {
+		writeval(stuff[MIN].filp, val);
+		writeval(stuff[MAX].filp, val);
+	}
 }
 
 static void checkit(void)
@@ -146,6 +169,7 @@ igt_simple_main
 		igt_assert(ret != -1);
 		junk->filp = fopen(path, junk->mode);
 		igt_require(junk->filp);
+		setbuf(junk->filp, NULL);
 
 		val = readval(junk->filp);
 		igt_assert(val >= 0);
@@ -173,17 +197,16 @@ igt_simple_main
 	checkit();
 
 	/* And some errors */
-	writeval(stuff[MIN].filp, frpn - 1);
-	writeval(stuff[MAX].filp, frp0 + 1000);
+	writeval_inval(stuff[MIN].filp, frpn - 1);
+	writeval_inval(stuff[MAX].filp, frp0 + 1000);
 	checkit();
 
-	writeval(stuff[MIN].filp, fmax + 1000);
-	writeval(stuff[MAX].filp, fmin - 1);
+	writeval_inval(stuff[MIN].filp, fmax + 1000);
+	writeval_inval(stuff[MAX].filp, fmin - 1);
 	checkit();
 
-	do_writeval(stuff[MIN].filp, 0x11111110, EINVAL);
-	do_writeval(stuff[MAX].filp, 0, EINVAL);
+	writeval_inval(stuff[MIN].filp, 0x11111110);
+	writeval_inval(stuff[MAX].filp, 0);
 
-	writeval(stuff[MIN].filp, origmin);
-	writeval(stuff[MAX].filp, origmax);
+	restore();
 }
-- 
1.8.5.2

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