pinctrl: Don't copy function name when requesting a pin

Instead, store a pointer to the currently assigned function. This allows us to delete the mux_requested variable from pin_desc; a pin is requested if its currently assigned function is non-NULL. When a pin is requested as a GPIO rather than a regular function, the assigned function name is dynamically constructed. In this case, we have to kstrdup() the dynamically constructed name, so that mux_function doesn't pointed at stack data. This requires pin_free to be told whether to free the mux_function pointer or not. This removes the hard-coded maximum function name length. Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

pinctrl: Don't copy function name when requesting a pin
Instead, store a pointer to the currently assigned function. This allows us to delete the mux_requested variable from pin_desc; a pin is requested if its currently assigned function is non-NULL. When a pin is requested as a GPIO rather than a regular function, the assigned function name is dynamically constructed. In this case, we have to kstrdup() the dynamically constructed name, so that mux_function doesn't pointed at stack data. This requires pin_free to be told whether to free the mux_function pointer or not. This removes the hard-coded maximum function name length. Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Stephen Warren · Linus Walleij
1 parent 9af1e44fb4
Showing 2 changed files with 24 additions and 15 deletions Side-by-side Diff
drivers/pinctrl/core.h
drivers/pinctrl/pinmux.c
@@ -59,8 +59,7 @@
 	spinlock_t lock;
 	/* These fields only added when supporting pinmux drivers */
 #ifdef CONFIG_PINMUX
-	bool	mux_requested;
-	char	mux_function[16];
+	const char *mux_function;
 #endif
 };
  
@@ -130,14 +130,13 @@
 	}
  
 	spin_lock(&desc->lock);
-	if (desc->mux_requested) {
+	if (desc->mux_function) {
 		spin_unlock(&desc->lock);
 		dev_err(&pctldev->dev,
 			"pin already requested\n");
 		goto out;
 	}
-	desc->mux_requested = true;
-	strncpy(desc->mux_function, function, sizeof(desc->mux_function));
+	desc->mux_function = function;
 	spin_unlock(&desc->lock);
  
 	/* Let each pin increase references to this module */
@@ -168,8 +167,7 @@
 out_free_pin:
 	if (status) {
 		spin_lock(&desc->lock);
-		desc->mux_requested = false;
-		desc->mux_function[0] = '\0';
+		desc->mux_function = NULL;
 		spin_unlock(&desc->lock);
 	}
 out:
  
@@ -184,8 +182,9 @@
  * pin_free() - release a single muxed in pin so something else can be muxed
  * @pctldev: pin controller device handling this pin
  * @pin: the pin to free
+ * @free_func: whether to free the pin's assigned function name string
  */
-static void pin_free(struct pinctrl_dev *pctldev, int pin)
+static void pin_free(struct pinctrl_dev *pctldev, int pin, int free_func)
 {
 	const struct pinmux_ops *ops = pctldev->desc->pmxops;
 	struct pin_desc *desc;
@@ -201,8 +200,9 @@
 		ops->free(pctldev, pin);
  
 	spin_lock(&desc->lock);
-	desc->mux_requested = false;
-	desc->mux_function[0] = '\0';
+	if (free_func)
+		kfree(desc->mux_function);
+	desc->mux_function = NULL;
 	spin_unlock(&desc->lock);
 	module_put(pctldev->owner);
 }
@@ -214,6 +214,7 @@
 int pinmux_request_gpio(unsigned gpio)
 {
 	char gpiostr[16];
+	const char *function;
 	struct pinctrl_dev *pctldev;
 	struct pinctrl_gpio_range *range;
 	int ret;
@@ -229,7 +230,15 @@
 	/* Conjure some name stating what chip and pin this is taken by */
 	snprintf(gpiostr, 15, "%s:%d", range->name, gpio);
  
-	return pin_request(pctldev, pin, gpiostr, true, range);
+	function = kstrdup(gpiostr, GFP_KERNEL);
+	if (!function)
+		return -EINVAL;
+
+	ret = pin_request(pctldev, pin, function, true, range);
+	if (ret < 0)
+		kfree(function);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(pinmux_request_gpio);
  
@@ -251,7 +260,7 @@
 	/* Convert to the pin controllers number space */
 	pin = gpio - range->base;
  
-	pin_free(pctldev, pin);
+	pin_free(pctldev, pin, true);
 }
 EXPORT_SYMBOL_GPL(pinmux_free_gpio);
  
@@ -351,7 +360,7 @@
 			/* On error release all taken pins */
 			i--; /* this pin just failed */
 			for (; i >= 0; i--)
-				pin_free(pctldev, pins[i]);
+				pin_free(pctldev, pins[i], false);
 			return -ENODEV;
 		}
 	}
@@ -381,7 +390,7 @@
 		return;
 	}
 	for (i = 0; i < num_pins; i++)
-		pin_free(pctldev, pins[i]);
+		pin_free(pctldev, pins[i], false);
 }
  
 /**
@@ -1013,7 +1022,8 @@
  
 		seq_printf(s, "pin %d (%s): %s\n", pin,
 			   desc->name ? desc->name : "unnamed",
-			   desc->mux_requested ? desc->mux_function : "UNCLAIMED");
+			   desc->mux_function ? desc->mux_function
+					      : "UNCLAIMED");
 	}
  
 	return 0;
...	...	@@ -59,8 +59,7 @@
59	59	spinlock_t lock;
60	60	/* These fields only added when supporting pinmux drivers */
61	61	#ifdef CONFIG_PINMUX
62		- bool mux_requested;
63		- char mux_function[16];
	62	+ const char *mux_function;
64	63	#endif
65	64	};
66	65
...	...	@@ -130,14 +130,13 @@
130	130	}
131	131
132	132	spin_lock(&desc->lock);
133		- if (desc->mux_requested) {
	133	+ if (desc->mux_function) {
134	134	spin_unlock(&desc->lock);
135	135	dev_err(&pctldev->dev,
136	136	"pin already requested\n");
137	137	goto out;
138	138	}
139		- desc->mux_requested = true;
140		- strncpy(desc->mux_function, function, sizeof(desc->mux_function));
	139	+ desc->mux_function = function;
141	140	spin_unlock(&desc->lock);
142	141
143	142	/* Let each pin increase references to this module */
...	...	@@ -168,8 +167,7 @@
168	167	out_free_pin:
169	168	if (status) {
170	169	spin_lock(&desc->lock);
171		- desc->mux_requested = false;
172		- desc->mux_function[0] = '\0';
	170	+ desc->mux_function = NULL;
173	171	spin_unlock(&desc->lock);
174	172	}
175	173	out:
176	174
...	...	@@ -184,8 +182,9 @@
184	182	* pin_free() - release a single muxed in pin so something else can be muxed
185	183	* @pctldev: pin controller device handling this pin
186	184	* @pin: the pin to free
	185	+ * @free_func: whether to free the pin's assigned function name string
187	186	*/
188		-static void pin_free(struct pinctrl_dev *pctldev, int pin)
	187	+static void pin_free(struct pinctrl_dev *pctldev, int pin, int free_func)
189	188	{
190	189	const struct pinmux_ops *ops = pctldev->desc->pmxops;
191	190	struct pin_desc *desc;
...	...	@@ -201,8 +200,9 @@
201	200	ops->free(pctldev, pin);
202	201
203	202	spin_lock(&desc->lock);
204		- desc->mux_requested = false;
205		- desc->mux_function[0] = '\0';
	203	+ if (free_func)
	204	+ kfree(desc->mux_function);
	205	+ desc->mux_function = NULL;
206	206	spin_unlock(&desc->lock);
207	207	module_put(pctldev->owner);
208	208	}
...	...	@@ -214,6 +214,7 @@
214	214	int pinmux_request_gpio(unsigned gpio)
215	215	{
216	216	char gpiostr[16];
	217	+ const char *function;
217	218	struct pinctrl_dev *pctldev;
218	219	struct pinctrl_gpio_range *range;
219	220	int ret;
...	...	@@ -229,7 +230,15 @@
229	230	/* Conjure some name stating what chip and pin this is taken by */
230	231	snprintf(gpiostr, 15, "%s:%d", range->name, gpio);
231	232
232		- return pin_request(pctldev, pin, gpiostr, true, range);
	233	+ function = kstrdup(gpiostr, GFP_KERNEL);
	234	+ if (!function)
	235	+ return -EINVAL;
	236	+
	237	+ ret = pin_request(pctldev, pin, function, true, range);
	238	+ if (ret < 0)
	239	+ kfree(function);
	240	+
	241	+ return ret;
233	242	}
234	243	EXPORT_SYMBOL_GPL(pinmux_request_gpio);
235	244
...	...	@@ -251,7 +260,7 @@
251	260	/* Convert to the pin controllers number space */
252	261	pin = gpio - range->base;
253	262
254		- pin_free(pctldev, pin);
	263	+ pin_free(pctldev, pin, true);
255	264	}
256	265	EXPORT_SYMBOL_GPL(pinmux_free_gpio);
257	266
...	...	@@ -351,7 +360,7 @@
351	360	/* On error release all taken pins */
352	361	i--; /* this pin just failed */
353	362	for (; i >= 0; i--)
354		- pin_free(pctldev, pins[i]);
	363	+ pin_free(pctldev, pins[i], false);
355	364	return -ENODEV;
356	365	}
357	366	}
...	...	@@ -381,7 +390,7 @@
381	390	return;
382	391	}
383	392	for (i = 0; i < num_pins; i++)
384		- pin_free(pctldev, pins[i]);
	393	+ pin_free(pctldev, pins[i], false);
385	394	}
386	395
387	396	/**
...	...	@@ -1013,7 +1022,8 @@
1013	1022
1014	1023	seq_printf(s, "pin %d (%s): %s\n", pin,
1015	1024	desc->name ? desc->name : "unnamed",
1016		- desc->mux_requested ? desc->mux_function : "UNCLAIMED");
	1025	+ desc->mux_function ? desc->mux_function
	1026	+ : "UNCLAIMED");
1017	1027	}
1018	1028
1019	1029	return 0;