On Sat, Mar 31, 2018 at 10:09:40PM +0200, Stefan Wahren wrote:
> The kernel would like to have all stack VLA usage removed[1]. The array
> here is fixed (declared with a const variable) but it appears like a VLA
> to the compiler. Also, currently we are putting 768 bytes on the
> stack. So save stack space and removes the VLA build warning by
> making it static.
>
> [1]: https://lkml.org/lkml/2018/3/7/621
>
> CC: Tobin C. Harding <m...@tobin.cc>
> Signed-off-by: Stefan Wahren <stefan.wah...@i2se.com>
> ---
> .../vc04_services/interface/vchiq_arm/vchiq_arm.c | 20
> ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> index 24d456b..f276437 100644
> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
> @@ -3414,13 +3414,18 @@ vchiq_release_service(VCHIQ_SERVICE_HANDLE_T handle)
> return ret;
> }
>
> +struct service_data_struct {
> + int fourcc;
> + int clientid;
> + int use_count;
> +};
> +
> void
> vchiq_dump_service_use_state(VCHIQ_STATE_T *state)
> {
> VCHIQ_ARM_STATE_T *arm_state = vchiq_platform_get_arm_state(state);
> + static struct service_data_struct service_data[64];
> int i, j = 0;
> - /* Only dump 64 services */
> - static const int local_max_services = 64;
> /* If there's more than 64 services, only dump ones with
> * non-zero counts */
> int only_nonzero = 0;
> @@ -3431,11 +3436,6 @@ vchiq_dump_service_use_state(VCHIQ_STATE_T *state)
> int peer_count;
> int vc_use_count;
> int active_services;
> - struct service_data_struct {
> - int fourcc;
> - int clientid;
> - int use_count;
> - } service_data[local_max_services];
>
> if (!arm_state)
> return;
> @@ -3446,10 +3446,10 @@ vchiq_dump_service_use_state(VCHIQ_STATE_T *state)
> peer_count = arm_state->peer_use_count;
> vc_use_count = arm_state->videocore_use_count;
> active_services = state->unused_service;
> - if (active_services > local_max_services)
> + if (active_services > ARRAY_SIZE(service_data))
> only_nonzero = 1;
>
> - for (i = 0; (i < active_services) && (j < local_max_services); i++) {
> + for (i = 0; (i < active_services) && (j < ARRAY_SIZE(service_data));
> i++) {
> VCHIQ_SERVICE_T *service_ptr = state->services[i];
>
> if (!service_ptr)
> @@ -3479,7 +3479,7 @@ vchiq_dump_service_use_state(VCHIQ_STATE_T *state)
> vchiq_log_warning(vchiq_susp_log_level, "Too many active "
> "services (%d). Only dumping up to first %d services "
> "with non-zero use-count", active_services,
> - local_max_services);
> + ARRAY_SIZE(service_data));
>
> for (i = 0; i < j; i++) {
> vchiq_log_warning(vchiq_susp_log_level,
> --
> 2.7.4
>
On a previous attempt to fix this VLA Linus commented that 64 was too
big (it equates to 768 bytes on the stack). Here is that email for your
reference
https://lkml.org/lkml/2018/3/9/744
I didn't understand what he meant by 'just do the stack size limitation'
Hope this helps,
Tobin.
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