linux-kernel - [PATCH v3 2/2] efi-pstore: Make efi-pstore return a unique id

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Date:	Wed, 28 Jan 2015 16:06:26 +0800
From:	HuKeping <hukeping@...wei.com>
To:	<gregkh@...uxfoundation.org>
CC:	<linux-kernel@...r.kernel.org>, <matt.fleming@...el.com>,
	<cbouatmailru@...il.com>, <ccross@...roid.com>,
	<keescook@...omium.org>, <tony.luck@...el.com>,
	<stable@...r.kernel.org>, <rob.herring@...xeda.com>,
	<cxie@...hat.com>, <sdu.liu@...wei.com>, <wangnan0@...wei.com>,
	<peifeiyue@...wei.com>
Subject: [PATCH v3 2/2] efi-pstore: Make efi-pstore return a unique id

From: Madper Xie <cxie@...hat.com>

Commit fdeadb43fdf1e7d5698c027b555c389174548e5a upstream.

Pstore fs expects that backends provide a unique id which could avoid
pstore making entries as duplication or denominating entries the same
name. So I combine the timestamp, part and count into id.

Signed-off-by: Madper Xie <cxie@...hat.com>
Cc: Seiji Aguchi <seiji.aguchi@....com>
Cc: stable@...r.kernel.org
Signed-off-by: Matt Fleming <matt.fleming@...el.com>
[hkp: Backported to 3.10: adjust context]
Signed-off-by: Hu Keping <hukeping@...wei.com>

---
 drivers/firmware/efi/efi-pstore.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index 66c0c76..c5163e3 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -38,6 +38,12 @@ struct pstore_read_data {
 	char **buf;
 };
 
+static inline u64 generic_id(unsigned long timestamp,
+			     unsigned int part, int count)
+{
+	return (timestamp * 100 + part) * 1000 + count;
+}
+
 static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 {
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
@@ -56,7 +62,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 
 	if (sscanf(name, "dump-type%u-%u-%d-%lu",
 		   cb_data->type, &part, &cnt, &time) == 4) {
-		*cb_data->id = part;
+		*cb_data->id = generic_id(time, part, cnt);
 		*cb_data->count = cnt;
 		cb_data->timespec->tv_sec = time;
 		cb_data->timespec->tv_nsec = 0;
@@ -67,7 +73,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 		 * which doesn't support holding
 		 * multiple logs, remains.
 		 */
-		*cb_data->id = part;
+		*cb_data->id = generic_id(time, part, 0);
 		*cb_data->count = 0;
 		cb_data->timespec->tv_sec = time;
 		cb_data->timespec->tv_nsec = 0;
@@ -185,14 +191,16 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 	char name[DUMP_NAME_LEN];
 	efi_char16_t efi_name[DUMP_NAME_LEN];
 	int found, i;
+	unsigned int part;
 
-	sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count,
-		time.tv_sec);
+	do_div(id, 1000);
+	part = do_div(id, 100);
+	sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);
 
 	for (i = 0; i < DUMP_NAME_LEN; i++)
 		efi_name[i] = name[i];
 
-	edata.id = id;
+	edata.id = part;
 	edata.type = type;
 	edata.count = count;
 	edata.time = time;
-- 
1.8.5.5

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