PCI/sysfs: Return -EINVAL consistently from "store" functions

Most of the "store" functions that handle userspace input via sysfs return
-EINVAL should the value fail validation and/or type conversion.  This
error code is a clear message to userspace that the value is not a valid
input.

However, some of the "show" functions return input parsing error codes
as-is, which may be either -EINVAL or -ERANGE.  The former would often be
from kstrtobool(), and the latter typically from other kstr*() functions
such as kstrtou8(), kstrtou32(), kstrtoint(), etc.

-EINVAL is commonly returned as the error code to indicate that the value
provided is invalid, but -ERANGE is not very useful in userspace.

Therefore, normalize the return error code to be -EINVAL for when the
validation and/or type conversion fails.

Link: https://lore.kernel.org/r/20210915230127.2495723-2-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

2 files changed, 18 insertions, 35 deletions

diff --git a/drivers/pci/endpoint/functions/pci-epf-ntb.c b/drivers/pci/endpoint/functions/pci-epf-ntb.c
index 8b4756159f15..e67489144349 100644
--- a/drivers/pci/endpoint/functions/pci-epf-ntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-ntb.c
@@ -1947,11 +1947,9 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item,	\
 	struct config_group *group = to_config_group(item);		\
 	struct epf_ntb *ntb = to_epf_ntb(group);			\
 	u32 val;							\
-	int ret;							\
 									\
-	ret = kstrtou32(page, 0, &val);					\
-	if (ret)							\
-		return ret;						\
+	if (kstrtou32(page, 0, &val) < 0)				\
+		return -EINVAL;						\
 									\
 	ntb->_name = val;						\
 									\
@@ -1980,11 +1978,9 @@ static ssize_t epf_ntb_##_name##_store(struct config_item *item,	\
 	struct device *dev = &ntb->epf->dev;				\
 	int win_no;							\
 	u64 val;							\
-	int ret;							\
 									\
-	ret = kstrtou64(page, 0, &val);					\
-	if (ret)							\
-		return ret;						\
+	if (kstrtou64(page, 0, &val) < 0)				\
+		return -EINVAL;						\
 									\
 	if (sscanf(#_name, "mw%d", &win_no) != 1)			\
 		return -EINVAL;						\
@@ -2005,11 +2001,9 @@ static ssize_t epf_ntb_num_mws_store(struct config_item *item,
 	struct config_group *group = to_config_group(item);
 	struct epf_ntb *ntb = to_epf_ntb(group);
 	u32 val;
-	int ret;
 
-	ret = kstrtou32(page, 0, &val);
-	if (ret)
-		return ret;
+	if (kstrtou32(page, 0, &val) < 0)
+		return -EINVAL;
 
 	if (val > MAX_MW)
 		return -EINVAL;
diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index 999911801877..19bc0e828c0c 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -175,9 +175,8 @@ static ssize_t pci_epc_start_store(struct config_item *item, const char *page,
 
 	epc = epc_group->epc;
 
-	ret = kstrtobool(page, &start);
-	if (ret)
-		return ret;
+	if (kstrtobool(page, &start) < 0)
+		return -EINVAL;
 
 	if (!start) {
 		pci_epc_stop(epc);
@@ -329,13 +328,11 @@ static ssize_t pci_epf_##_name##_store(struct config_item *item,	       \
 				       const char *page, size_t len)	       \
 {									       \
 	u32 val;							       \
-	int ret;							       \
 	struct pci_epf *epf = to_pci_epf_group(item)->epf;		       \
 	if (WARN_ON_ONCE(!epf->header))					       \
 		return -EINVAL;						       \
-	ret = kstrtou32(page, 0, &val);					       \
-	if (ret)							       \
-		return ret;						       \
+	if (kstrtou32(page, 0, &val) < 0)				       \
+		return -EINVAL;						       \
 	epf->header->_name = val;					       \
 	return len;							       \
 }
@@ -345,13 +342,11 @@ static ssize_t pci_epf_##_name##_store(struct config_item *item,	       \
 				       const char *page, size_t len)	       \
 {									       \
 	u16 val;							       \
-	int ret;							       \
 	struct pci_epf *epf = to_pci_epf_group(item)->epf;		       \
 	if (WARN_ON_ONCE(!epf->header))					       \
 		return -EINVAL;						       \
-	ret = kstrtou16(page, 0, &val);					       \
-	if (ret)							       \
-		return ret;						       \
+	if (kstrtou16(page, 0, &val) < 0)				       \
+		return -EINVAL;						       \
 	epf->header->_name = val;					       \
 	return len;							       \
 }
@@ -361,13 +356,11 @@ static ssize_t pci_epf_##_name##_store(struct config_item *item,	       \
 				       const char *page, size_t len)	       \
 {									       \
 	u8 val;								       \
-	int ret;							       \
 	struct pci_epf *epf = to_pci_epf_group(item)->epf;		       \
 	if (WARN_ON_ONCE(!epf->header))					       \
 		return -EINVAL;						       \
-	ret = kstrtou8(page, 0, &val);					       \
-	if (ret)							       \
-		return ret;						       \
+	if (kstrtou8(page, 0, &val) < 0)				       \
+		return -EINVAL;						       \
 	epf->header->_name = val;					       \
 	return len;							       \
 }
@@ -376,11 +369,9 @@ static ssize_t pci_epf_msi_interrupts_store(struct config_item *item,
 					    const char *page, size_t len)
 {
 	u8 val;
-	int ret;
 
-	ret = kstrtou8(page, 0, &val);
-	if (ret)
-		return ret;
+	if (kstrtou8(page, 0, &val) < 0)
+		return -EINVAL;
 
 	to_pci_epf_group(item)->epf->msi_interrupts = val;
 
@@ -398,11 +389,9 @@ static ssize_t pci_epf_msix_interrupts_store(struct config_item *item,
 					     const char *page, size_t len)
 {
 	u16 val;
-	int ret;
 
-	ret = kstrtou16(page, 0, &val);
-	if (ret)
-		return ret;
+	if (kstrtou16(page, 0, &val) < 0)
+		return -EINVAL;
 
 	to_pci_epf_group(item)->epf->msix_interrupts = val;