[PATCH v3] nvmem: properly handle returned value from nvmem_reg_read

[Mathieu Malaterre]

Function ânvmem_reg_readâ can return a non zero value indicating an
error. This returned value should be read and error propagated to
ânvmem_cell_prepare_write_bufferâ. Silence a gcc warning (using W=1):

  drivers/nvmem/core.c:1093:9: warning: variable ârcâ set but not used [-Wunused-but-set-variable]

Signed-off-by: Mathieu Malaterre <malat@xxxxxxxxxx>
---
v3: return exact error code instead of EINVAL, tweak commit message a bit
v2: prefer ERR_PTR(-EINVAL) over a simple return NULL

 drivers/nvmem/core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index b05aa8e81303..1e28597138c8 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -1107,6 +1107,8 @@ static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
 
 		/* setup the first byte with lsb bits from nvmem */
 		rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
+		if (rc)
+			goto err;
 		*b++ |= GENMASK(bit_offset - 1, 0) & v;
 
 		/* setup rest of the byte if any */
@@ -1125,11 +1127,16 @@ static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
 		/* setup the last byte with msb bits from nvmem */
 		rc = nvmem_reg_read(nvmem,
 				    cell->offset + cell->bytes - 1, &v, 1);
+		if (rc)
+			goto err;
 		*p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
 
 	}
 
 	return buf;
+err:
+	kfree(buf);
+	return ERR_PTR(rc);
 }
 
 /**
-- 
2.11.0