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Subject[PATCH v4] pstore: Avoid duplicate call of persistent_ram_zap()
Date
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);

@@ -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
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