[PATCH] libbpf: Remove unnecessary conversion to bool

From: Kaixu Xia <redacted>

Fix following warning from coccinelle:

./tools/lib/bpf/libbpf.c:1478:43-48: WARNING: conversion to bool not needed here

Signed-off-by: Kaixu Xia <redacted>
---
 tools/lib/bpf/libbpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 313034117070..fb9625077983 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c

@@ -1475,7 +1475,7 @@ static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
 				ext->name, value);
 			return -EINVAL;
 		}
-		*(bool *)ext_val = value == 'y' ? true : false;
+		*(bool *)ext_val = value == 'y';
 		break;
 	case KCFG_TRISTATE:
 		if (value == 'y')

-- 
2.20.0

On Thu, Nov 5, 2020 at 11:12 PM [off-list ref] wrote:

I actually did this intentionally. x = y == z; pattern looked too
obscure to my taste, tbh.

                break;
        case KCFG_TRISTATE:
                if (value == 'y')
--
2.20.0

On Fri, 2020-11-06 at 13:32 -0800, Andrii Nakryiko wrote:

On Thu, Nov 5, 2020 at 11:12 PM [off-list ref] wrote:

quoted

Fix following warning from coccinelle:
./tools/lib/bpf/libbpf.c:1478:43-48: WARNING: conversion to bool not needed here

[]

quoted

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c

[]

quoted

@@ -1475,7 +1475,7 @@ static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,

                                ext->name, value);
                        return -EINVAL;
                }
-               *(bool *)ext_val = value == 'y' ? true : false;
+               *(bool *)ext_val = value == 'y';

I actually did this intentionally. x = y == z; pattern looked too
obscure to my taste, tbh.

It's certainly a question of taste and obviously there is nothing
wrong with yours.

Maybe adding parentheses makes the below look less obscure to you?

	x = (y == z);

My taste would run to something like:
---
 tools/lib/bpf/libbpf.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 313034117070..5d9c9c8d50c9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c

@@ -1469,25 +1469,34 @@ static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
 			      char value)
 {
 	switch (ext->kcfg.type) {
-	case KCFG_BOOL:
+	case KCFG_BOOL: {
+		bool *p = ext_val;
+
 		if (value == 'm') {
 			pr_warn("extern (kcfg) %s=%c should be tristate or char\n",
 				ext->name, value);
 			return -EINVAL;
 		}
-		*(bool *)ext_val = value == 'y' ? true : false;
+		*p = (value == 'y');
 		break;
-	case KCFG_TRISTATE:
+	}
+	case KCFG_TRISTATE: {
+		enum libbpf_tristate *p = ext_val;
+
 		if (value == 'y')
-			*(enum libbpf_tristate *)ext_val = TRI_YES;
+			*p = TRI_YES;
 		else if (value == 'm')
-			*(enum libbpf_tristate *)ext_val = TRI_MODULE;
+			*p = TRI_MODULE;
 		else /* value == 'n' */
-			*(enum libbpf_tristate *)ext_val = TRI_NO;
+			*p = TRI_NO;
 		break;
-	case KCFG_CHAR:
-		*(char *)ext_val = value;
+	}
+	case KCFG_CHAR: {
+		char *p = ext_val;
+
+		*p = value;
 		break;
+	}
 	case KCFG_UNKNOWN:
 	case KCFG_INT:
 	case KCFG_CHAR_ARR:

On Fri, Nov 6, 2020 at 1:50 PM Joe Perches [off-list ref] wrote:

On Fri, 2020-11-06 at 13:32 -0800, Andrii Nakryiko wrote:

quoted

On Thu, Nov 5, 2020 at 11:12 PM [off-list ref] wrote:

quoted

Fix following warning from coccinelle:
./tools/lib/bpf/libbpf.c:1478:43-48: WARNING: conversion to bool not needed here

[]

quoted

quoted

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c

[]

quoted

quoted

@@ -1475,7 +1475,7 @@ static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,
                                ext->name, value);
                        return -EINVAL;
                }
-               *(bool *)ext_val = value == 'y' ? true : false;
+               *(bool *)ext_val = value == 'y';

I actually did this intentionally. x = y == z; pattern looked too
obscure to my taste, tbh.

It's certainly a question of taste and obviously there is nothing
wrong with yours.

Maybe adding parentheses makes the below look less obscure to you?

        x = (y == z);

Yeah, I think this would be explicit enough. But let's keep the *(bool
*) cast and keep switch code shorter and without extra {} block.

My taste would run to something like:
---
 tools/lib/bpf/libbpf.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

[...]

From: Joe Perches

Sent: 06 November 2020 21:50

On Fri, 2020-11-06 at 13:32 -0800, Andrii Nakryiko wrote:

quoted

On Thu, Nov 5, 2020 at 11:12 PM [off-list ref] wrote:

quoted

Fix following warning from coccinelle:
./tools/lib/bpf/libbpf.c:1478:43-48: WARNING: conversion to bool not needed here

[]

quoted

quoted

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c

[]

quoted

quoted

@@ -1475,7 +1475,7 @@ static int set_kcfg_value_tri(struct extern_desc *ext, void *ext_val,

                                ext->name, value);
                        return -EINVAL;
                }
-               *(bool *)ext_val = value == 'y' ? true : false;
+               *(bool *)ext_val = value == 'y';

I actually did this intentionally. x = y == z; pattern looked too
obscure to my taste, tbh.

It's certainly a question of taste and obviously there is nothing
wrong with yours.

Maybe adding parentheses makes the below look less obscure to you?

	x = (y == z);

That just leads to people thinking conditionals need to be in parentheses
and then getting the priorities for ?: all wrong as in:
	x = a + (b == c) ? d : e;

It would (probably) be better to make 'ext_val' be a union type
(probably a 'pointer to a union' rather than a union of pointers)
so that all the casts go away.

	David

-
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