Messages in this thread | | | From | Kees Cook <> | Date | Tue, 30 Oct 2018 14:21:59 -0700 | Subject | Re: [PATCH v4] pstore: Avoid duplicate call of persistent_ram_zap() |
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On Tue, Oct 30, 2018 at 12:52 AM, Peng Wang <wangpeng15@xiaomi.com> 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>
Thanks! I've applied this to my devel branch. I'll have it in linux-next once -rc2 lands.
-Kees
> --- > 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); > > @@ -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; > } > } else { > pr_debug("no valid data in buffer (sig = 0x%08x)\n", > prz->buffer->sig); > + prz->buffer->sig = sig; > } > > /* Rewind missing or invalid memory area. */ > - prz->buffer->sig = sig; > persistent_ram_zap(prz); > > return 0; > diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h > index 602d64725222..6e94980357d2 100644 > --- a/include/linux/pstore_ram.h > +++ b/include/linux/pstore_ram.h > @@ -30,6 +30,7 @@ > * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required. > */ > #define PRZ_FLAG_NO_LOCK BIT(0) > +#define PRZ_FLAG_ZAP_OLD BIT(1) > > struct persistent_ram_buffer; > struct rs_control; > -- > 2.19.1 >
-- Kees Cook
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