[PATCH v6 05/18] pstore/ram: Refactor ftrace buffer merging

From: Kees Cook
Date: Sat May 09 2020 - 19:41:20 EST


This changes the ftrace record merging code to be agnostic of
pstore/ram, as the first step to making it available as a generic
routine for other backends to use, such as pstore/zone.

Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
fs/pstore/ram.c | 29 +++++++++++++++++------------
1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index 7f956053f4e5..672ad80646c5 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -172,8 +172,9 @@ static bool prz_ok(struct persistent_ram_zone *prz)
persistent_ram_ecc_string(prz, NULL, 0));
}

-static ssize_t ftrace_log_combine(struct persistent_ram_zone *dest,
- struct persistent_ram_zone *src)
+static
+ssize_t ftrace_log_combine(char **dest_log, size_t *dest_log_size,
+ const char *src_log, size_t src_log_size)
{
size_t dest_size, src_size, total, dest_off, src_off;
size_t dest_idx = 0, src_idx = 0, merged_idx = 0;
@@ -181,19 +182,19 @@ static ssize_t ftrace_log_combine(struct persistent_ram_zone *dest,
struct pstore_ftrace_record *drec, *srec, *mrec;
size_t record_size = sizeof(struct pstore_ftrace_record);

- dest_off = dest->old_log_size % record_size;
- dest_size = dest->old_log_size - dest_off;
+ dest_off = *dest_log_size % record_size;
+ dest_size = *dest_log_size - dest_off;

- src_off = src->old_log_size % record_size;
- src_size = src->old_log_size - src_off;
+ src_off = src_log_size % record_size;
+ src_size = src_log_size - src_off;

total = dest_size + src_size;
merged_buf = kmalloc(total, GFP_KERNEL);
if (!merged_buf)
return -ENOMEM;

- drec = (struct pstore_ftrace_record *)(dest->old_log + dest_off);
- srec = (struct pstore_ftrace_record *)(src->old_log + src_off);
+ drec = (struct pstore_ftrace_record *)(*dest_log + dest_off);
+ srec = (struct pstore_ftrace_record *)(src_log + src_off);
mrec = (struct pstore_ftrace_record *)(merged_buf);

while (dest_size > 0 && src_size > 0) {
@@ -217,9 +218,9 @@ static ssize_t ftrace_log_combine(struct persistent_ram_zone *dest,
src_size -= record_size;
}

- kfree(dest->old_log);
- dest->old_log = merged_buf;
- dest->old_log_size = total;
+ kfree(*dest_log);
+ *dest_log = merged_buf;
+ *dest_log_size = total;

return 0;
}
@@ -295,7 +296,11 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
tmp_prz->corrected_bytes +=
prz_next->corrected_bytes;
tmp_prz->bad_blocks += prz_next->bad_blocks;
- size = ftrace_log_combine(tmp_prz, prz_next);
+
+ size = ftrace_log_combine(&tmp_prz->old_log,
+ &tmp_prz->old_log_size,
+ prz_next->old_log,
+ prz_next->old_log_size);
if (size)
goto out;
}
--
2.20.1