[PATCH] tests/core_setmaster: Handle the test even if cards are non-continuous

[Bommu Krishnaiah]

Although most of userspace assumes drm cards to be populated continously,

this assumption may not be always true. After hot unpluging and
repluging of card

the card may be non-continous.  To address such scenarios where the
cards can be non-continous

modify the tweak_perm function to loop all possible
cardnumbers(card0-card255) to confirm are they populated or not.

Problem Description:
The test fails after running the `core_hotunplug at hot*` subtest, where
card0 is missing.
This leads to a failure in the subsequent `master-drop-set-user` test.

Command sequence for reproducing the issue:
- Check available cards: `ls /dev/dri/`
	- Output: by-path  card0  renderD128
- Run the test: `# ./core_hotunplug --r hotrebind-lateclose`
- Check again: ‘ls /dev/dri/’
	- Output after failure: by-path  card1  renderD129
- Run the test: `# ./core_setmaster --r master-drop-set-user`

This failures on both XE and i915 for above sequence.

Signed-off-by: Bommu Krishnaiah <krishnaiah.bommu at intel.com>
Cc: Emil Velikov <emil.l.velikov at gmail.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray at intel.com>
Cc: Kamil Konieczny <kamil.konieczny at linux.intel.com>
---
 tests/core_setmaster.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tests/core_setmaster.c b/tests/core_setmaster.c
index 9c2083f66..a2758e2f2 100644
--- a/tests/core_setmaster.c
+++ b/tests/core_setmaster.c
@@ -116,9 +116,10 @@ static unsigned tweak_perm(uint8_t *saved_perm, unsigned max_perm, bool save)
 	for (i = 0; i < max_perm; i++) {
 		snprintf(path, sizeof(path), "/dev/dri/card%u", i);
 
-		/* Existing userspace assumes there's no gaps, do the same. */
+		/* Userspace cannot always have continuous card0...N due to
+		 * dynamic unloading or removal of cards */
 		if (stat(path, &st) != 0)
-			break;
+			continue;
 
 		if (save) {
 			/* Save and toggle */
-- 
2.25.1