Messages in this thread |  | | From | Kees Cook <> | Date | Mon, 10 Oct 2016 16:59:47 -0700 | Subject | Re: [PATCH 5/7] ramoops: Split ftrace buffer space into per-CPU zones |
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On Sun, Oct 9, 2016 at 10:15 AM, Joel Fernandes <joelaf@google.com> wrote: > On Fri, Oct 7, 2016 at 10:28 PM, Joel Fernandes <joelaf@google.com> wrote: >> If FTRACE_PER_CPU flag is passed to ramoops pdata, split the space into >> multiple zones depending on the number of CPUs. >> >> This speeds up the performance of function tracing by about 280% in my tests as >> we avoid the locking. The trade off being lesser space available per CPU. Let >> the ramoops user decide which option they want based on pdata flag. >> >> Signed-off-by: Joel Fernandes <joelaf@google.com> >> --- >> fs/pstore/ram.c | 70 +++++++++++++++++++++++++++++++++++----------- >> include/linux/pstore_ram.h | 3 ++ >> 2 files changed, 56 insertions(+), 17 deletions(-) >> >> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c > [..] >> @@ -391,14 +418,21 @@ static void ramoops_free_przs(struct ramoops_context *cxt) >> { >> int i; >> >> - if (!cxt->przs) >> - return; >> + /* Free dump PRZs */ >> + if (cxt->przs) { >> + for (i = 0; i < cxt->max_dump_cnt; i++) >> + persistent_ram_free(cxt->przs[i]); >> >> - for (i = 0; i < cxt->max_dump_cnt; i++) >> - persistent_ram_free(cxt->przs[i]); >> + kfree(cxt->przs); >> + cxt->max_dump_cnt = 0; >> + } >> >> - kfree(cxt->przs); >> - cxt->max_dump_cnt = 0; >> + /* Free ftrace PRZs */ >> + if (cxt->fprzs) { >> + for (i = 0; i < nr_cpu_ids; i++) >> + persistent_ram_free(cxt->przs[i]); > > I am supposed to free fprzs[i] here, instead of przs[i]. Also need to > check flag and free correct number of zones. Will fix for v2, sorry > about that.
I think the cpu id needs to be bounds-checked against the size of the allocation. In theory, CPU hot-plug could grow the number of CPUs after pstore is initialized.
-Kees
-- Kees Cook Nexus Security
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