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

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Date:   Sat,  9 May 2020 16:40:50 -0700
From:   Kees Cook <keescook@...omium.org>
To:     WeiXiong Liao <liaoweixiong@...winnertech.com>
Cc:     Kees Cook <keescook@...omium.org>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Rob Herring <robh@...nel.org>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org
Subject: [PATCH v6 05/18] pstore/ram: Refactor ftrace buffer merging

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@...omium.org>
---
 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