diff mbox series

[v2,02/11] chardev/baum: Use definitions to avoid dynamic stack allocation

Message ID 20220819153931.3147384-3-peter.maydell@linaro.org
State Superseded
Headers show
Series misc: Remove variable-length arrays on the stack | expand

Commit Message

Peter Maydell Aug. 19, 2022, 3:39 p.m. UTC 
From: Philippe Mathieu-Daudé <philmd@redhat.com>

We know 'x * y' will be at most 'X_MAX * Y_MAX' (which is not
a big value, it is actually 84). Instead of having the compiler
use variable-length array, declare an array able to hold the
maximum 'x * y'.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 chardev/baum.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Richard Henderson Oct. 24, 2022, 11:12 p.m. UTC | #1 
On 8/20/22 01:39, Peter Maydell wrote:
> From: Philippe Mathieu-Daudé<philmd@redhat.com>
> 
> We know 'x * y' will be at most 'X_MAX * Y_MAX' (which is not
> a big value, it is actually 84). Instead of having the compiler
> use variable-length array, declare an array able to hold the
> maximum 'x * y'.
> 
> Signed-off-by: Philippe Mathieu-Daudé<philmd@redhat.com>
> Reviewed-by: Marc-André Lureau<marcandre.lureau@redhat.com>
> Reviewed-by: Samuel Thibault<samuel.thibault@ens-lyon.org>
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> ---
>   chardev/baum.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~
diff mbox series

Patch

diff --git a/chardev/baum.c b/chardev/baum.c
index 6d538808a0f..6a210ffd815 100644
--- a/chardev/baum.c
+++ b/chardev/baum.c
@@ -383,9 +383,9 @@  static int baum_eat_packet(BaumChardev *baum, const uint8_t *buf, int len)
     switch (req) {
     case BAUM_REQ_DisplayData:
     {
-        uint8_t cells[baum->x * baum->y], c;
-        uint8_t text[baum->x * baum->y];
-        uint8_t zero[baum->x * baum->y];
+        uint8_t cells[X_MAX * Y_MAX], c;
+        uint8_t text[X_MAX * Y_MAX];
+        uint8_t zero[X_MAX * Y_MAX];
         int cursor = BRLAPI_CURSOR_OFF;
         int i;
 
@@ -408,7 +408,7 @@  static int baum_eat_packet(BaumChardev *baum, const uint8_t *buf, int len)
         }
         timer_del(baum->cellCount_timer);
 
-        memset(zero, 0, sizeof(zero));
+        memset(zero, 0, baum->x * baum->y);
 
         brlapi_writeArguments_t wa = {
             .displayNumber = BRLAPI_DISPLAY_DEFAULT,