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SubjectRe: [PATCH v1 01/16] perf header: Make nodes dynamic in write_mem_topology
On Thu, May 25, 2023 at 7:39 PM Ian Rogers <irogers@google.com> wrote:
>
> On Thu, May 25, 2023 at 12:15 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > 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
>
> Not sure I follow. The reallocarray tests for failure, frees nodes and
> returns -ENOMEM on error.

Right, but I think it would leak the nodes when the
memory_node__read() fails.

Thanks,
Namhyung

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