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SubjectRe: [PATCH v1 01/16] perf header: Make nodes dynamic in write_mem_topology
On Thu, May 25, 2023 at 12:12 AM Ian Rogers <irogers@google.com> wrote:
>
> Avoid a large static array, dynamically allocate the nodes avoiding a
> hard coded limited as well.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/header.c | 33 +++++++++++++++++++++------------
> 1 file changed, 21 insertions(+), 12 deletions(-)
>
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 2dde3ca20de5..80593ed8c79b 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -24,6 +24,7 @@
> #include <bpf/libbpf.h>
> #endif
> #include <perf/cpumap.h>
> +#include <tools/libc_compat.h> // reallocarray
>
> #include "dso.h"
> #include "evlist.h"
> @@ -1396,13 +1397,14 @@ static int memory_node__sort(const void *a, const void *b)
> return na->node - nb->node;
> }
>
> -static int build_mem_topology(struct memory_node *nodes, u64 size, u64 *cntp)
> +static int build_mem_topology(struct memory_node **nodesp, u64 *cntp)
> {
> char path[PATH_MAX];
> struct dirent *ent;
> DIR *dir;
> - u64 cnt = 0;
> int ret = 0;
> + size_t cnt = 0, size = 0;
> + struct memory_node *nodes = NULL;
>
> scnprintf(path, PATH_MAX, "%s/devices/system/node/",
> sysfs__mountpoint());
> @@ -1426,16 +1428,24 @@ static int build_mem_topology(struct memory_node *nodes, u64 size, u64 *cntp)
> if (r != 1)
> continue;
>
> - if (WARN_ONCE(cnt >= size,
> - "failed to write MEM_TOPOLOGY, way too many nodes\n")) {
> - closedir(dir);
> - return -1;
> - }
> + if (cnt >= size) {
> + struct memory_node *new_nodes =
> + reallocarray(nodes, cnt + 4, sizeof(*nodes));
>
> + if (!new_nodes) {
> + pr_err("Failed to write MEM_TOPOLOGY, size %zd nodes\n", size);
> + free(nodes);
> + closedir(dir);
> + return -ENOMEM;
> + }
> + nodes = new_nodes;
> + size += 4;
> + }
> ret = memory_node__read(&nodes[cnt++], idx);

I think you need to handle error cases here.

Thanks,
Namhyung


> }
>
> *cntp = cnt;
> + *nodesp = nodes;
> closedir(dir);
>
> if (!ret)
> @@ -1444,8 +1454,6 @@ static int build_mem_topology(struct memory_node *nodes, u64 size, u64 *cntp)
> return ret;
> }
>
> -#define MAX_MEMORY_NODES 2000
> -
> /*
> * The MEM_TOPOLOGY holds physical memory map for every
> * node in system. The format of data is as follows:
> @@ -1464,8 +1472,8 @@ static int build_mem_topology(struct memory_node *nodes, u64 size, u64 *cntp)
> static int write_mem_topology(struct feat_fd *ff __maybe_unused,
> struct evlist *evlist __maybe_unused)
> {
> - static struct memory_node nodes[MAX_MEMORY_NODES];
> - u64 bsize, version = 1, i, nr;
> + struct memory_node *nodes = NULL;
> + u64 bsize, version = 1, i, nr = 0;
> int ret;
>
> ret = sysfs__read_xll("devices/system/memory/block_size_bytes",
> @@ -1473,7 +1481,7 @@ static int write_mem_topology(struct feat_fd *ff __maybe_unused,
> if (ret)
> return ret;
>
> - ret = build_mem_topology(&nodes[0], MAX_MEMORY_NODES, &nr);
> + ret = build_mem_topology(&nodes, &nr);
> if (ret)
> return ret;
>
> @@ -1508,6 +1516,7 @@ static int write_mem_topology(struct feat_fd *ff __maybe_unused,
> }
>
> out:
> + free(nodes);
> return ret;
> }
>
> --
> 2.40.1.698.g37aff9b760-goog
>

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