1 files changed, 35 insertions, 15 deletions

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index f371e03cf3bf..11c7a171c0a1 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -297,6 +297,7 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
 					  GFP_KERNEL);
 			if (!tmp_prz)
 				return -ENOMEM;
+			prz = tmp_prz;
 			free_prz = true;
 
 			while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt) {
@@ -319,7 +320,6 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
 					goto out;
 			}
 			record->id = 0;
-			prz = tmp_prz;
 		}
 	}
 
@@ -433,6 +433,17 @@ static int notrace ramoops_pstore_write(struct pstore_record *record)
 
 	prz = cxt->dprzs[cxt->dump_write_cnt];
 
+	/*
+	 * Since this is a new crash dump, we need to reset the buffer in
+	 * case it still has an old dump present. Without this, the new dump
+	 * will get appended, which would seriously confuse anything trying
+	 * to check dump file contents. Specifically, ramoops_read_kmsg_hdr()
+	 * expects to find a dump header in the beginning of buffer data, so
+	 * we must to reset the buffer values, in order to ensure that the
+	 * header will be written to the beginning of the buffer.
+	 */
+	persistent_ram_zap(prz);
+
 	/* Build header and append record contents. */
 	hlen = ramoops_write_kmsg_hdr(prz, record);
 	size = record->size;
@@ -801,27 +812,36 @@ static int ramoops_probe(struct platform_device *pdev)
 
 	cxt->pstore.data = cxt;
 	/*
-	 * Since bufsize is only used for dmesg crash dumps, it
-	 * must match the size of the dprz record (after PRZ header
-	 * and ECC bytes have been accounted for).
+	 * Prepare frontend flags based on which areas are initialized.
+	 * For ramoops_init_przs() cases, the "max count" variable tells
+	 * if there are regions present. For ramoops_init_prz() cases,
+	 * the single region size is how to check.
 	 */
-	cxt->pstore.bufsize = cxt->dprzs[0]->buffer_size;
-	cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
-	if (!cxt->pstore.buf) {
-		pr_err("cannot allocate pstore crash dump buffer\n");
-		err = -ENOMEM;
-		goto fail_clear;
-	}
-	spin_lock_init(&cxt->pstore.buf_lock);
-
-	cxt->pstore.flags = PSTORE_FLAGS_DMESG;
+	cxt->pstore.flags = 0;
+	if (cxt->max_dump_cnt)
+		cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
 	if (cxt->console_size)
 		cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
-	if (cxt->ftrace_size)
+	if (cxt->max_ftrace_cnt)
 		cxt->pstore.flags |= PSTORE_FLAGS_FTRACE;
 	if (cxt->pmsg_size)
 		cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
 
+	/*
+	 * Since bufsize is only used for dmesg crash dumps, it
+	 * must match the size of the dprz record (after PRZ header
+	 * and ECC bytes have been accounted for).
+	 */
+	if (cxt->pstore.flags & PSTORE_FLAGS_DMESG) {
+		cxt->pstore.bufsize = cxt->dprzs[0]->buffer_size;
+		cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
+		if (!cxt->pstore.buf) {
+			pr_err("cannot allocate pstore crash dump buffer\n");
+			err = -ENOMEM;
+			goto fail_clear;
+		}
+	}
+
 	err = pstore_register(&cxt->pstore);
 	if (err) {
 		pr_err("registering with pstore failed\n");