Re: [PATCH v2] powerpc/perf: Fix loop exit condition in nest_imc_event_init

[Madhavan Srinivasan <maddy@linux.vnet.ibm.com>]

On 18/12/18 11:50 AM, Anju T Sudhakar wrote:
> The data structure (i.e struct imc_mem_info) to hold the memory address
> information for nest imc units is allocated based on the number of nodes
> in the system.
>
> nest_imc_event_init() traverse this struct array to calculate the memory
> base address for the event-cpu. If we fail to find a match for the event
> cpu's chip-id in imc_mem_info struct array, then the do-while loop will
> iterate until we crash.
>
> Fix this by changing the loop exit condition based on the number of
> non zero vbase elements in the array, since the allocation is done for
> nr_chips + 1.

Reviewed-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>

B/w we will also need this patch to go along
https://patchwork.ozlabs.org/patch/1003669/

These 2 fixes need to go to stable also.

> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Fixes: 885dcd709ba91 ( powerpc/perf: Add nest IMC PMU support)
> Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com>
> ---
>   arch/powerpc/perf/imc-pmu.c               | 2 +-
>   arch/powerpc/platforms/powernv/opal-imc.c | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
> index 4f34c75..d1009fe 100644
> --- a/arch/powerpc/perf/imc-pmu.c
> +++ b/arch/powerpc/perf/imc-pmu.c
> @@ -508,7 +508,7 @@ static int nest_imc_event_init(struct perf_event *event)
>   			break;
>   		}
>   		pcni++;
> -	} while (pcni);
> +	} while (pcni->vbase != 0);
>
>   	if (!flag)
>   		return -ENODEV;
> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c b/arch/powerpc/platforms/powernv/opal-imc.c
> index 58a0794..3d27f02 100644
> --- a/arch/powerpc/platforms/powernv/opal-imc.c
> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
> @@ -127,7 +127,7 @@ static int imc_get_mem_addr_nest(struct device_node *node,
>   								nr_chips))
>   		goto error;
>
> -	pmu_ptr->mem_info = kcalloc(nr_chips, sizeof(*pmu_ptr->mem_info),
> +	pmu_ptr->mem_info = kcalloc(nr_chips + 1, sizeof(*pmu_ptr->mem_info),
>   				    GFP_KERNEL);
>   	if (!pmu_ptr->mem_info)
>   		goto error;