virt: hvc_sysfs: Fix build for Linux v6.16

In Linux v6.16, the 'bin_attribute' argument to the 'read' and 'write'
function pointers of the 'bin_attribute' structure was made const. Add a
test to conftest to detect this and update the Tegra HVC SYSFS driver
accordingly.

JIRA LINQPJ14-60

Change-Id: I74b88bc0d1ed55eca1565386b38d16ff65626132
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3375213
(cherry picked from commit fef581cb0bac2d1468a710927771be9fa027f6e0)
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nv-oot/+/3461880
Reviewed-by: Brad Griffis <bgriffis@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/virt/tegra/hvc_sysfs.c

@@ -88,7 +88,12 @@ static int nvlog_buffer_mmap(struct file *fp, struct kobject *ko,
 }
 
 static ssize_t nvlog_region_size_read(struct file *fp, struct kobject *ko,
-	struct bin_attribute *attr, char *buf, loff_t pos, size_t size)
+#if defined(NV_BIN_ATTRIBUTE_STRUCT_READWRITE_HAS_CONST_BIN_ATTRIBUTE_ARG)
+	const struct bin_attribute *attr,
+#else
+	struct bin_attribute *attr,
+#endif
+	char *buf, loff_t pos, size_t size)
 {
 	struct nvlog_shmem_info *info = container_of(attr, struct nvlog_shmem_info, region_size_attr);
 
@@ -97,7 +102,12 @@ static ssize_t nvlog_region_size_read(struct file *fp, struct kobject *ko,
 }
 
 static ssize_t nvlog_buffer_size_read(struct file *fp, struct kobject *ko,
-	struct bin_attribute *attr, char *buf, loff_t pos, size_t size)
+#if defined(NV_BIN_ATTRIBUTE_STRUCT_READWRITE_HAS_CONST_BIN_ATTRIBUTE_ARG)
+	const struct bin_attribute *attr,
+#else
+	struct bin_attribute *attr,
+#endif
+	char *buf, loff_t pos, size_t size)
 {
 	struct nvlog_shmem_info *info = container_of(attr, struct nvlog_shmem_info, buf_size_attr);
 
@@ -106,7 +116,12 @@ static ssize_t nvlog_buffer_size_read(struct file *fp, struct kobject *ko,
 }
 
 static ssize_t nvlog_buffer_count_read(struct file *fp, struct kobject *ko,
-	struct bin_attribute *attr, char *buf, loff_t pos, size_t size)
+#if defined(NV_BIN_ATTRIBUTE_STRUCT_READWRITE_HAS_CONST_BIN_ATTRIBUTE_ARG)
+	const struct bin_attribute *attr,
+#else
+	struct bin_attribute *attr,
+#endif
+	char *buf, loff_t pos, size_t size)
 {
 	struct nvlog_shmem_info *info = container_of(attr, struct nvlog_shmem_info, buf_count_attr);
 
@@ -296,7 +311,12 @@ static int hvc_create_sysfs(
 }
 
 static ssize_t log_mask_read(struct file *fp, struct kobject *ko,
-	struct bin_attribute *attr, char *buf, loff_t pos, size_t size)
+#if defined(NV_BIN_ATTRIBUTE_STRUCT_READWRITE_HAS_CONST_BIN_ATTRIBUTE_ARG)
+	const struct bin_attribute *attr,
+#else
+	struct bin_attribute *attr,
+#endif
+	char *buf, loff_t pos, size_t size)
 {
 	uint64_t value = 0;
 
@@ -312,7 +332,12 @@ static ssize_t log_mask_read(struct file *fp, struct kobject *ko,
 }
 
 static ssize_t log_mask_write(struct file *fp, struct kobject *ko,
-	struct bin_attribute *attr, char *buf, loff_t pos, size_t size)
+#if defined(NV_BIN_ATTRIBUTE_STRUCT_READWRITE_HAS_CONST_BIN_ATTRIBUTE_ARG)
+	const struct bin_attribute *attr,
+#else
+	struct bin_attribute *attr,
+#endif
+	char *buf, loff_t pos, size_t size)
 {
 	uint64_t type, value;
 

scripts/conftest/Makefile

@@ -93,6 +93,7 @@ NV_CONFTEST_FUNCTION_COMPILE_TESTS += __alloc_pages_bulk_has_no_page_list_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += __assign_str_has_no_src_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += aperture_remove_all_conflicting_devices
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += bin_attribute_struct_mmap_has_const_bin_attribute_arg
+NV_CONFTEST_FUNCTION_COMPILE_TESTS += bin_attribute_struct_readwrite_has_const_bin_attribute_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += blk_execute_rq_has_no_gendisk_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += blk_mq_alloc_disk_for_queue
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += blk_mq_alloc_queue

scripts/conftest/conftest.sh

@@ -6588,6 +6588,26 @@ compile_test() {
                     "NV_BIN_ATTRIBUTE_STRUCT_MMAP_HAS_CONST_BIN_ATTRIBUTE_ARG" "" "types"
         ;;
 
+        bin_attribute_struct_readwrite_has_const_bin_attribute_arg)
+            #
+            # Determine if the 'bin_attribute' structure 'read' and 'write'
+            # function pointers have a const 'struct bin_attribute' argument.
+            #
+            # This change was made in Linux v6.16 by commit 97d06802d10a
+            # ("sysfs: constify bin_attribute argument of bin_attribute::read/write()").
+            #
+            CODE="
+            #include <linux/sysfs.h>
+            void conftest(struct bin_attribute *attr) {
+                    ssize_t (*fn)(struct file *, struct kobject *,
+                                  const struct bin_attribute *,
+                                  char *, loff_t, size_t) = attr->read;
+            }"
+
+            compile_check_conftest "$CODE" \
+                    "NV_BIN_ATTRIBUTE_STRUCT_READWRITE_HAS_CONST_BIN_ATTRIBUTE_ARG" "" "types"
+        ;;
+
         blk_execute_rq_has_no_gendisk_arg)
             #
             # Determine if the function blk_execute_rq() has an argument of