[PATCH i-g-t 4/5] lib/igt_sriov_device: Add helper functions for VF range validation

[Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>]

Add __is_valid_range() to check if a VF range is valid. Introduce
igt_sriov_random_vf_in_range() to get a random VF number within a
specified range. Update for_random_sriov_vf to use the new helper
functions for better range handling.

Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz@intel.com>
Cc: Adam Miszczak <adam.miszczak@linux.intel.com>
Cc: Jakub Kolakowski <jakub1.kolakowski@intel.com>
Cc: Lukasz Laguna <lukasz.laguna@intel.com>
Cc: Michał Wajdeczko <michal.wajdeczko@intel.com>
Cc: Michał Winiarski <michal.winiarski@intel.com>
Cc: Narasimha C V <narasimha.c.v@intel.com>
Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
Cc: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
Cc: Tomasz Lis <tomasz.lis@intel.com>
Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>
---
 lib/igt_sriov_device.h | 82 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 75 insertions(+), 7 deletions(-)

diff --git a/lib/igt_sriov_device.h b/lib/igt_sriov_device.h
index 4b63ceb22..de25a7d98 100644
--- a/lib/igt_sriov_device.h
+++ b/lib/igt_sriov_device.h
@@ -34,6 +34,45 @@ int igt_sriov_device_sysfs_open(int pf, unsigned int vf_num);
 bool igt_sriov_device_reset_exists(int pf, unsigned int vf_num);
 bool igt_sriov_device_reset(int pf, unsigned int vf_num);
 
+/**
+ * __is_valid_range - Helper to check VF range is valid
+ * @start_vf: Starting VF number
+ * @end_vf: Ending VF number
+ * @total_vfs: Total number of VFs
+ *
+ * Return: true if the range is valid, false otherwise.
+ */
+static inline bool __is_valid_range(unsigned int start_vf, unsigned int end_vf,
+				    unsigned int total_vfs)
+{
+	return !igt_warn_on_f(start_vf > end_vf || end_vf > total_vfs || start_vf == 0,
+			      "start_vf=%u, end_vf=%u, total_vfs=%u\n",
+			      start_vf, end_vf, total_vfs);
+}
+
+/**
+ * igt_sriov_random_vf_in_range - Get a random VF number within a specified range
+ * @pf_fd: PF device file descriptor
+ * @start: Starting VF number in the range
+ * @end: Ending VF number in the range
+ *
+ * Returns a random VF number within the specified range [start, end].
+ * If the range is invalid (start > end, end > total VFs,
+ * or start == 0), the function returns 0.
+ *
+ * Return: A random VF number within the range, or 0 if the range is invalid.
+ */
+static inline unsigned int
+igt_sriov_random_vf_in_range(int pf_fd, unsigned int start, unsigned int end)
+{
+	unsigned int total_vfs = igt_sriov_get_total_vfs(pf_fd);
+
+	if (!__is_valid_range(start, end, total_vfs))
+		return 0;
+
+	return start + random() % (end - start + 1);
+}
+
 /**
  * for_each_sriov_vf - Helper for running code on each VF
  * @__pf_fd: PF device file descriptor
@@ -48,17 +87,46 @@ bool igt_sriov_device_reset(int pf, unsigned int vf_num);
 #define for_each_sriov_num_vfs for_each_sriov_vf
 
 /**
- * for_random_sriov_vf - Helper for running code on random VF
+ * for_random_sriov_vf_in_range - Iterate over a random VF in a specified range
+ * @__pf_fd: PF device file descriptor
+ * @__start: Starting VF number in the range
+ * @__end: Ending VF number in the range
+ * @__vf_num: Variable to store the random VF number
+ *
+ * Iterates over a random VF number within the specified range [__start, __end].
+ * The loop runs only if the range is valid and a random
+ * VF number is successfully selected.
+ */
+#define for_random_sriov_vf_in_range(__pf_fd, __start, __end, __vf_num) \
+	for (unsigned int __vf_num = igt_sriov_random_vf_in_range(__pf_fd, __start, __end); \
+	     __vf_num != 0; __vf_num = 0)
+
+/**
+ * for_random_sriov_vf_starting_from - Iterate over a random VF starting from a specified VF
+ * @__pf_fd: PF device file descriptor
+ * @__start: Starting VF number
+ * @__vf_num: Variable to store the random VF number
+ *
+ * This macro iterates over a random VF number starting from the specified
+ * VF number @__start to the total number of VFs associated with the given
+ * PF @__pf_fd.
+ */
+#define for_random_sriov_vf_starting_from(__pf_fd, __start, __vf_num) \
+	for_random_sriov_vf_in_range(__pf_fd, __start, igt_sriov_get_total_vfs(__pf_fd), __vf_num)
+
+/**
+ * for_random_sriov_vf - Iterate over a random VF for a given PF
  * @__pf_fd: PF device file descriptor
- * @__vf_num: stores random VF
+ * @__vf_num: Variable to store the random VF number
  *
- * Helper allows to run code using random VF number (stored in @__vf_num)
- * picked from the range of all VFs associated with given PF @__pf_fd.
+ * Iterates over a random VF number selected from the range
+ * of all VFs associated with the given PF @__pf_fd. The loop runs only
+ * if a random VF number is successfully selected.
  */
 #define for_random_sriov_vf(__pf_fd, __vf_num) \
-	for (unsigned int __vf_num = 1 + random() % igt_sriov_get_total_vfs(__pf_fd), __tmp = 0; \
-	     __tmp < 1; \
-	     ++__tmp)
+	for_random_sriov_vf_in_range(__pf_fd, 1, igt_sriov_get_total_vfs(__pf_fd), __vf_num)
+
+/* for_random_sriov_num_vfs - Alias for for_random_sriov_vf */
 #define for_random_sriov_num_vfs for_random_sriov_vf
 
 /**
-- 
2.31.1