[PATCH 0/3] mmc: block: Cleanup mmc_blk_probe() path

[PATCH 0/3] mmc: block: Cleanup mmc_blk_probe() path

[Ulf Hansson]

While working on fixing KASAN splats for the mmc block device driver, I stumbled
over a couple of annoying things in the mmc_blk_probe() path. This series takes
care of them.

Ulf Hansson (3):
  mmc: block: Drop use of unlikely() in mmc_blk_probe()
  mmc: block: Simplify logging during probe about added partitions
  mmc: block: Fix error path in mmc_blk_probe()

 drivers/mmc/core/block.c | 49 ++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 24 deletions(-)

-- 
2.25.1

[PATCH 1/3] mmc: block: Drop use of unlikely() in mmc_blk_probe()

[Ulf Hansson]

mmc_blk_probe() isn't a hotpath, which makes it's questionable to use
unlikely(). Therefore let's simply drop it.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/core/block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 8e6a623b35de..dc6b2e8f4f95 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2888,7 +2888,7 @@ static int mmc_blk_probe(struct mmc_card *card)
 
 	card->complete_wq = alloc_workqueue("mmc_complete",
 					WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
-	if (unlikely(!card->complete_wq)) {
+	if (!card->complete_wq) {
 		pr_err("Failed to create mmc completion workqueue");
 		return -ENOMEM;
 	}
-- 
2.25.1

[PATCH 2/3] mmc: block: Simplify logging during probe about added partitions

[Ulf Hansson]

To simplify the code, move the logging into the common mmc_blk_alloc_req()
and drop the rather useless information about the partition type/id.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/core/block.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index dc6b2e8f4f95..39308b35a1fb 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2261,6 +2261,7 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
 {
 	struct mmc_blk_data *md;
 	int devidx, ret;
+	char cap_str[10];
 
 	devidx = ida_simple_get(&mmc_blk_ida, 0, max_devices, GFP_KERNEL);
 	if (devidx < 0) {
@@ -2365,6 +2366,12 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
 		blk_queue_write_cache(md->queue.queue, true, true);
 	}
 
+	string_get_size((u64)size, 512, STRING_UNITS_2,
+			cap_str, sizeof(cap_str));
+	pr_info("%s: %s %s %s %s\n",
+		md->disk->disk_name, mmc_card_id(card), mmc_card_name(card),
+		cap_str, md->read_only ? "(ro)" : "");
+
 	return md;
 
  err_putdisk:
@@ -2407,7 +2414,6 @@ static int mmc_blk_alloc_part(struct mmc_card *card,
 			      const char *subname,
 			      int area_type)
 {
-	char cap_str[10];
 	struct mmc_blk_data *part_md;
 
 	part_md = mmc_blk_alloc_req(card, disk_to_dev(md->disk), size, default_ro,
@@ -2417,11 +2423,6 @@ static int mmc_blk_alloc_part(struct mmc_card *card,
 	part_md->part_type = part_type;
 	list_add(&part_md->part, &md->part);
 
-	string_get_size((u64)get_capacity(part_md->disk), 512, STRING_UNITS_2,
-			cap_str, sizeof(cap_str));
-	pr_info("%s: %s %s partition %u %s\n",
-	       part_md->disk->disk_name, mmc_card_id(card),
-	       mmc_card_name(card), part_md->part_type, cap_str);
 	return 0;
 }
 
@@ -2558,9 +2559,8 @@ static int mmc_blk_alloc_rpmb_part(struct mmc_card *card,
 	string_get_size((u64)size, 512, STRING_UNITS_2,
 			cap_str, sizeof(cap_str));
 
-	pr_info("%s: %s %s partition %u %s, chardev (%d:%d)\n",
-		rpmb_name, mmc_card_id(card),
-		mmc_card_name(card), EXT_CSD_PART_CONFIG_ACC_RPMB, cap_str,
+	pr_info("%s: %s %s %s, chardev (%d:%d)\n",
+		rpmb_name, mmc_card_id(card), mmc_card_name(card), cap_str,
 		MAJOR(mmc_rpmb_devt), rpmb->id);
 
 	return 0;
@@ -2876,7 +2876,6 @@ static void mmc_blk_remove_debugfs(struct mmc_card *card,
 static int mmc_blk_probe(struct mmc_card *card)
 {
 	struct mmc_blk_data *md, *part_md;
-	char cap_str[10];
 
 	/*
 	 * Check that the card supports the command class(es) we need.
@@ -2897,12 +2896,6 @@ static int mmc_blk_probe(struct mmc_card *card)
 	if (IS_ERR(md))
 		return PTR_ERR(md);
 
-	string_get_size((u64)get_capacity(md->disk), 512, STRING_UNITS_2,
-			cap_str, sizeof(cap_str));
-	pr_info("%s: %s %s %s %s\n",
-		md->disk->disk_name, mmc_card_id(card), mmc_card_name(card),
-		cap_str, md->read_only ? "(ro)" : "");
-
 	if (mmc_blk_alloc_parts(card, md))
 		goto out;
 
-- 
2.25.1

[PATCH 3/3] mmc: block: Fix error path in mmc_blk_probe()

[Ulf Hansson]

Returning zero to indicate success, when we actually have failed to probe
is wrong. As a matter of fact, it leads to that mmc_blk_remove() gets
called at a card removal and then triggers "NULL pointer dereference"
splats. This is because mmc_blk_remove() relies on data structures and
pointers to be setup from mmc_blk_probe(), of course.

There have been no errors reported about this, which is most likely because
mmc_blk_probe() never fails like this. Nevertheless, let's fix the code by
propagating the error codes correctly and prevent us from leaking memory by
calling also destroy_workqueue() in the error path.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/core/block.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 39308b35a1fb..02b656305042 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -2876,6 +2876,7 @@ static void mmc_blk_remove_debugfs(struct mmc_card *card,
 static int mmc_blk_probe(struct mmc_card *card)
 {
 	struct mmc_blk_data *md, *part_md;
+	int ret = 0;
 
 	/*
 	 * Check that the card supports the command class(es) we need.
@@ -2893,19 +2894,24 @@ static int mmc_blk_probe(struct mmc_card *card)
 	}
 
 	md = mmc_blk_alloc(card);
-	if (IS_ERR(md))
-		return PTR_ERR(md);
+	if (IS_ERR(md)) {
+		ret = PTR_ERR(md);
+		goto out_free;
+	}
 
-	if (mmc_blk_alloc_parts(card, md))
+	ret = mmc_blk_alloc_parts(card, md);
+	if (ret)
 		goto out;
 
 	dev_set_drvdata(&card->dev, md);
 
-	if (mmc_add_disk(md))
+	ret = mmc_add_disk(md);
+	if (ret)
 		goto out;
 
 	list_for_each_entry(part_md, &md->part, part) {
-		if (mmc_add_disk(part_md))
+		ret = mmc_add_disk(part_md);
+		if (ret)
 			goto out;
 	}
 
@@ -2926,10 +2932,12 @@ static int mmc_blk_probe(struct mmc_card *card)
 
 	return 0;
 
- out:
+out:
 	mmc_blk_remove_parts(card, md);
 	mmc_blk_remove_req(md);
-	return 0;
+out_free:
+	destroy_workqueue(card->complete_wq);
+	return ret;
 }
 
 static void mmc_blk_remove(struct mmc_card *card)
-- 
2.25.1