tracing: Fix compilation warning on arm32

On arm32, size_t is defined to be unsigned int, while PAGE_SIZE is
unsigned long. This hence triggers a compilation warning as min()
asserts the type of two operands to be equal. Casting PAGE_SIZE to size_t
solves this issue and works on other target architectures as well.

Compilation warning details:

kernel/trace/trace.c: In function 'tracing_splice_read_pipe':
./include/linux/minmax.h:20:28: warning: comparison of distinct pointer types lacks a cast
  (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                            ^
./include/linux/minmax.h:26:4: note: in expansion of macro '__typecheck'
   (__typecheck(x, y) && __no_side_effects(x, y))
    ^~~~~~~~~~~

...

kernel/trace/trace.c:6771:8: note: in expansion of macro 'min'
        min((size_t)trace_seq_used(&iter->seq),
        ^~~

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250526013731.1198030-1-pantaixi@huaweicloud.com
Fixes: f5178c41bb43 ("tracing: Fix oob write in trace_seq_to_buffer()")
Reviewed-by: Jeongjun Park <aha310510@gmail.com>
Signed-off-by: Pan Taixi <pantaixi@huaweicloud.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2c1764ed87b05920f5bfe9786bce6fb9a3d5ab40..b60d495c2a7987ddc70e0c9adcf59556e5ad880e 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6891,7 +6891,7 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
                ret = trace_seq_to_buffer(&iter->seq,
                                          page_address(spd.pages[i]),
                                          min((size_t)trace_seq_used(&iter->seq),
-                                                 PAGE_SIZE));
+                                                 (size_t)PAGE_SIZE));
                if (ret < 0) {
                        __free_page(spd.pages[i]);
                        break;