lkml.org 
[lkml]   [2018]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH -next v2 04/12] pstore: Avoid duplicate call of persistent_ram_zap()
Date
From: Peng Wang <wangpeng15@xiaomi.com>

When initialing a prz, if invalid data is found (no PERSISTENT_RAM_SIG),
the function call path looks 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>
[kees: minor tweak to exit path and commit log]
Signed-off-by: Kees Cook <keescook@chromium.org>
---
fs/pstore/ram.c | 4 +---
fs/pstore/ram_core.c | 15 +++++++++------
include/linux/pstore_ram.h | 1 +
3 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index e02a9039b5ea..768759841491 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..23ca6f2c98a0 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -489,6 +489,7 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
struct persistent_ram_ecc_info *ecc_info)
{
int ret;
+ bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);

ret = persistent_ram_init_ecc(prz, ecc_info);
if (ret)
@@ -498,23 +499,25 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,

if (prz->buffer->sig == sig) {
if (buffer_size(prz) > prz->buffer_size ||
- buffer_start(prz) > buffer_size(prz))
+ buffer_start(prz) > buffer_size(prz)) {
pr_info("found existing invalid buffer, size %zu, start %zu\n",
buffer_size(prz), buffer_start(prz));
- else {
+ zap = true;
+ } else {
pr_debug("found existing buffer, size %zu, start %zu\n",
buffer_size(prz), buffer_start(prz));
persistent_ram_save_old(prz);
- return 0;
}
} else {
pr_debug("no valid data in buffer (sig = 0x%08x)\n",
prz->buffer->sig);
+ prz->buffer->sig = sig;
+ zap = true;
}

- /* Rewind missing or invalid memory area. */
- prz->buffer->sig = sig;
- persistent_ram_zap(prz);
+ /* Reset missing, invalid, or single-use memory area. */
+ if (zap)
+ 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;
--
2.17.1
\
 
 \ /
  Last update: 2018-11-30 00:09    [W:0.063 / U:1.988 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site