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Message-ID: <20231219-strncpy-drivers-iio-proximity-sx9324-c-v4-1-d49ed29ee952@google.com>
Date: Tue, 19 Dec 2023 21:34:15 +0000
From: Justin Stitt <justinstitt@...gle.com>
To: Jonathan Cameron <jic23@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>
Cc: Stephen Boyd <swboyd@...omium.org>, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH v4] iio: sx9324: avoid copying property strings
We're doing some needless string copies when trying to assign the proper
`prop` string. We can make `prop` a const char* and simply assign to
string literals.
For the case where a format string is used, let's extract the parsing
logic out into sx9324_parse_phase_prop(). We no longer need to create
copies or allocate new memory.
sx9324_parse_phase_prop() will simply return the default def value if it
fails.
This also cleans up some deprecated strncpy() uses [1].
Furthermore, let's clean up this code further by removing some unused
defines:
| #define SX9324_PIN_DEF "semtech,ph0-pin"
| #define SX9324_RESOLUTION_DEF "semtech,ph01-resolution"
| #define SX9324_PROXRAW_DEF "semtech,ph01-proxraw-strength"
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Changes in v4:
- use u8 return type (thanks Stephen)
- remove unused defines (thanks Stephen et al.)
- tweaks to sx9324_parse_phase_prop related to defaults (thanks Stephen)
- Link to v3: https://lore.kernel.org/r/20231212-strncpy-drivers-iio-proximity-sx9324-c-v3-1-b8ae12fc8a5d@google.com
Changes in v3:
- extract logic into sx9324_parse_phase_prop() and use string literals
(thanks Stephen)
- rebase onto mainline bee0e7762ad2c602
- Link to v2: https://lore.kernel.org/r/20231026-strncpy-drivers-iio-proximity-sx9324-c-v2-1-cee6e5db700c@google.com
Changes in v2:
- make prop a const char* and do simple assignments (thanks Jonathan)
- rebase onto 3a568e3a961ba330
- Link to v1: https://lore.kernel.org/r/20230921-strncpy-drivers-iio-proximity-sx9324-c-v1-1-4e8d28fd1e7c@google.com
---
---
drivers/iio/proximity/sx9324.c | 70 ++++++++++++++++++++++++------------------
1 file changed, 40 insertions(+), 30 deletions(-)
diff --git a/drivers/iio/proximity/sx9324.c b/drivers/iio/proximity/sx9324.c
index 438f9c9aba6e..3daad7167c63 100644
--- a/drivers/iio/proximity/sx9324.c
+++ b/drivers/iio/proximity/sx9324.c
@@ -873,6 +873,29 @@ static int sx9324_init_compensation(struct iio_dev *indio_dev)
20000, 2000000);
}
+static u8 sx9324_parse_phase_prop(struct device *dev,
+ struct sx_common_reg_default *reg_def,
+ const char *prop)
+{
+ unsigned int pin_defs[SX9324_NUM_PINS];
+ int count, ret, pin;
+ u32 raw = 0;
+
+ count = device_property_count_u32(dev, prop);
+ if (count != ARRAY_SIZE(pin_defs))
+ return reg_def->def;
+ ret = device_property_read_u32_array(dev, prop, pin_defs,
+ ARRAY_SIZE(pin_defs));
+ if (ret)
+ return reg_def->def;
+
+ for (pin = 0; pin < SX9324_NUM_PINS; pin++)
+ raw |= (pin_defs[pin] << (2 * pin)) &
+ SX9324_REG_AFE_PH0_PIN_MASK(pin);
+
+ return raw;
+}
+
static const struct sx_common_reg_default *
sx9324_get_default_reg(struct device *dev, int idx,
struct sx_common_reg_default *reg_def)
@@ -881,38 +904,29 @@ sx9324_get_default_reg(struct device *dev, int idx,
"highest" };
static const char * const sx9324_csidle[] = { "hi-z", "hi-z", "gnd",
"vdd" };
-#define SX9324_PIN_DEF "semtech,ph0-pin"
-#define SX9324_RESOLUTION_DEF "semtech,ph01-resolution"
-#define SX9324_PROXRAW_DEF "semtech,ph01-proxraw-strength"
- unsigned int pin_defs[SX9324_NUM_PINS];
- char prop[] = SX9324_PROXRAW_DEF;
u32 start = 0, raw = 0, pos = 0;
- int ret, count, ph, pin;
- const char *res;
+ const char *prop, *res;
+ int ret;
memcpy(reg_def, &sx9324_default_regs[idx], sizeof(*reg_def));
sx_common_get_raw_register_config(dev, reg_def);
switch (reg_def->reg) {
case SX9324_REG_AFE_PH0:
+ reg_def->def = sx9324_parse_phase_prop(dev, reg_def,
+ "semtech,ph0-pin");
+ break;
case SX9324_REG_AFE_PH1:
+ reg_def->def = sx9324_parse_phase_prop(dev, reg_def,
+ "semtech,ph1-pin");
+ break;
case SX9324_REG_AFE_PH2:
+ reg_def->def = sx9324_parse_phase_prop(dev, reg_def,
+ "semtech,ph2-pin");
+ break;
case SX9324_REG_AFE_PH3:
- ph = reg_def->reg - SX9324_REG_AFE_PH0;
- snprintf(prop, ARRAY_SIZE(prop), "semtech,ph%d-pin", ph);
-
- count = device_property_count_u32(dev, prop);
- if (count != ARRAY_SIZE(pin_defs))
- break;
- ret = device_property_read_u32_array(dev, prop, pin_defs,
- ARRAY_SIZE(pin_defs));
- if (ret)
- break;
-
- for (pin = 0; pin < SX9324_NUM_PINS; pin++)
- raw |= (pin_defs[pin] << (2 * pin)) &
- SX9324_REG_AFE_PH0_PIN_MASK(pin);
- reg_def->def = raw;
+ reg_def->def = sx9324_parse_phase_prop(dev, reg_def,
+ "semtech,ph3-pin");
break;
case SX9324_REG_AFE_CTRL0:
ret = device_property_read_string(dev,
@@ -937,11 +951,9 @@ sx9324_get_default_reg(struct device *dev, int idx,
case SX9324_REG_AFE_CTRL4:
case SX9324_REG_AFE_CTRL7:
if (reg_def->reg == SX9324_REG_AFE_CTRL4)
- strncpy(prop, "semtech,ph01-resolution",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph01-resolution";
else
- strncpy(prop, "semtech,ph23-resolution",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph23-resolution";
ret = device_property_read_u32(dev, prop, &raw);
if (ret)
@@ -1012,11 +1024,9 @@ sx9324_get_default_reg(struct device *dev, int idx,
case SX9324_REG_PROX_CTRL0:
case SX9324_REG_PROX_CTRL1:
if (reg_def->reg == SX9324_REG_PROX_CTRL0)
- strncpy(prop, "semtech,ph01-proxraw-strength",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph01-proxraw-strength";
else
- strncpy(prop, "semtech,ph23-proxraw-strength",
- ARRAY_SIZE(prop));
+ prop = "semtech,ph23-proxraw-strength";
ret = device_property_read_u32(dev, prop, &raw);
if (ret)
break;
---
base-commit: bee0e7762ad2c6025b9f5245c040fcc36ef2bde8
change-id: 20230921-strncpy-drivers-iio-proximity-sx9324-c-8c3437676039
Best regards,
--
Justin Stitt <justinstitt@...gle.com>
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