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authorPeng Wang <wangpeng15@xiaomi.com>2018-10-30 15:52:34 +0800
committerKees Cook <keescook@chromium.org>2018-12-03 16:52:35 -0800
commit7684bd334d9d4ca4f09873e88d9c0131a2cf6c3b (patch)
tree2ccb5d56ff8945abd6d2a85bb70e8804ba6bef9c /fs/pstore/ram_core.c
parentb77fa617a2ff4d6beccad3d3d4b3a1f2d10368aa (diff)
pstore: Avoid duplicate call of persistent_ram_zap()
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>
Diffstat (limited to 'fs/pstore/ram_core.c')
-rw-r--r--fs/pstore/ram_core.c15
1 files changed, 9 insertions, 6 deletions
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;
}