Messages in this thread | | | Date | Tue, 30 Oct 2018 15:16:05 -0700 | From | Joel Fernandes <> | Subject | Re: [PATCH v4] pstore: Avoid duplicate call of persistent_ram_zap() |
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On Tue, Oct 30, 2018 at 02:52:43PM -0700, Kees Cook wrote: > On Tue, Oct 30, 2018 at 2:38 PM, Joel Fernandes <joel@joelfernandes.org> wrote: > > On Tue, Oct 30, 2018 at 03:52:34PM +0800, Peng Wang wrote: > >> When initialing prz with invalid data in buffer(no PERSISTENT_RAM_SIG), > >> function call path is like this: > >> > >> ramoops_init_prz -> > >> | > >> |-> persistent_ram_new -> persistent_ram_post_init -> persistent_ram_zap > >> | > >> |-> persistent_ram_zap > >> > >> As we can see, persistent_ram_zap() is called twice. > >> We can avoid this by adding an option to persistent_ram_new(), and > >> only call persistent_ram_zap() when it is needed. > >> > >> Signed-off-by: Peng Wang <wangpeng15@xiaomi.com> > >> --- > >> fs/pstore/ram.c | 4 +--- > >> fs/pstore/ram_core.c | 5 +++-- > >> include/linux/pstore_ram.h | 1 + > >> 3 files changed, 5 insertions(+), 5 deletions(-) > >> > >> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c > >> index ffcff6516e89..b51901f97dc2 100644 > >> --- a/fs/pstore/ram.c > >> +++ b/fs/pstore/ram.c > >> @@ -640,7 +640,7 @@ static int ramoops_init_prz(const char *name, > >> > >> label = kasprintf(GFP_KERNEL, "ramoops:%s", name); > >> *prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info, > >> - cxt->memtype, 0, label); > >> + cxt->memtype, PRZ_FLAG_ZAP_OLD, label); > >> if (IS_ERR(*prz)) { > >> int err = PTR_ERR(*prz); > > > > Looks good to me except the minor comment below: > > > >> > >> @@ -649,8 +649,6 @@ static int ramoops_init_prz(const char *name, > >> return err; > >> } > >> > >> - persistent_ram_zap(*prz); > >> - > >> *paddr += sz; > >> > >> return 0; > >> diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c > >> index 12e21f789194..2ededd1ea1c2 100644 > >> --- a/fs/pstore/ram_core.c > >> +++ b/fs/pstore/ram_core.c > >> @@ -505,15 +505,16 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, > >> pr_debug("found existing buffer, size %zu, start %zu\n", > >> buffer_size(prz), buffer_start(prz)); > >> persistent_ram_save_old(prz); > >> - return 0; > >> + if (!(prz->flags & PRZ_FLAG_ZAP_OLD)) > >> + return 0; > > > > This could be written differently. > > > > We could just do: > > > > if (prz->flags & PRZ_FLAG_ZAP_OLD) > > persistent_ram_zap(prz); > > > > And remove the zap from below below. > > I actually rearranged things a little to avoid additional round-trips > on the mailing list. :) > > > Since Kees already took this patch, I can just patch this in my series if > > Kees and you are Ok with this suggestion. > > I've put it up here: > https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=pstore/devel&id=ac564e023248e3f4d87917b91d12376ddfca5000
Cool, it LGTM :)
- Joel
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