Re: [PATCH] ath10k: fix a NULL vs IS_ERR() check

On Mon, Nov 26, 2018 at 10:24:38AM +0200, Kalle Valo wrote:

Dan Carpenter [off-list ref] writes:

quoted

The devm_memremap() function doesn't return NULLs, it returns error
pointers.

Fixes: ba94c753ccb4 ("ath10k: add QMI message handshake for wcn3990 client")
Signed-off-by: Dan Carpenter <redacted>
---
 drivers/net/wireless/ath/ath10k/qmi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/qmi.c b/drivers/net/wireless/ath/ath10k/qmi.c
index f0429bee35c2..37b3bd629f48 100644
--- a/drivers/net/wireless/ath/ath10k/qmi.c
+++ b/drivers/net/wireless/ath/ath10k/qmi.c

@@ -931,9 +931,9 @@ static int ath10k_qmi_setup_msa_resources(struct ath10k_qmi *qmi, u32 msa_size)
 		qmi->msa_mem_size = resource_size(&r);
 		qmi->msa_va = devm_memremap(dev, qmi->msa_pa, qmi->msa_mem_size,
 					    MEMREMAP_WT);
-		if (!qmi->msa_va) {
+		if (IS_ERR(qmi->msa_va)) {
 			dev_err(dev, "failed to map memory region: %pa\n", &r.start);
-			return -EBUSY;
+			return PTR_ERR(qmi->msa_va);

That's a very good find!

But how has this even worked before?

This only changes the error path.  Presumably it always succeeds in real
life.

regards,
dan carpenter