[PATCH] powerpc/xive: Initialize symbol before usage

Function xive_native_get_ipi() might uses chip_id without it being
initialized. This gives the following error on 'smatch' tool:

	error: uninitialized symbol 'chip_id'

This patch simply sets chip_id initial value to 0.

CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
 arch/powerpc/sysdev/xive/native.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/sysdev/xive/native.c b/arch/powerpc/sysdev/xive/native.c
index 311185b9960a..fc56673a3c0f 100644
--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c

@@ -239,7 +239,7 @@ static bool xive_native_match(struct device_node *node)
 static int xive_native_get_ipi(unsigned int cpu, struct xive_cpu *xc)
 {
 	struct device_node *np;
-	unsigned int chip_id;
+	unsigned int chip_id = 0;
 	s64 irq;
 
 	/* Find the chip ID */

-- 
2.16.3

Hi Breno,

Breno Leitao [off-list ref] writes:

Function xive_native_get_ipi() might uses chip_id without it being
initialized. This gives the following error on 'smatch' tool:

	error: uninitialized symbol 'chip_id'

Which is correct, it can be used uninitialised. I'm surprised GCC
doesn't warn about it.

This patch simply sets chip_id initial value to 0.

I'd prefer we fixed it differently, by explicitly initialising to zero
at the appropriate place in the code.

The current code is:

	/* Find the chip ID */
	np = of_get_cpu_node(cpu, NULL);
	if (np) {
		if (of_property_read_u32(np, "ibm,chip-id", &chip_id) < 0)
			chip_id = 0;
	}

Where if np is NULL then we don't initialise chip_id.

Which could be:

	np = of_get_cpu_node(cpu, NULL);
        if (of_property_read_u32(np, "ibm,chip-id", &chip_id) < 0)
                chip_id = 0;

Because of_property_read_u32() will just return an error if np is NULL.

It's also missing an of_node_put() of np, you should do a separate patch
to fix that. You can just do it unconditionally after the
of_property_read_u32().

cheers

C=C3=A9dric Le Goater [off-list ref] writes:

On 08/23/2018 05:24 AM, Michael Ellerman wrote:

quoted

Breno Leitao [off-list ref] writes:

quoted

diff --git a/arch/powerpc/sysdev/xive/native.c b/arch/powerpc/sysdev/xi=

ve/native.c

quoted

quoted

index 311185b9960a..fc56673a3c0f 100644

--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c

@@ -239,7 +239,7 @@ static bool xive_native_match(struct device_node *n=

ode)

quoted

quoted

 static int xive_native_get_ipi(unsigned int cpu, struct xive_cpu *xc)
 {
 	struct device_node *np;
-	unsigned int chip_id;
+	unsigned int chip_id =3D 0;
 	s64 irq;
=20=20
 	/* Find the chip ID */

=20
The current code is:
=20
	/* Find the chip ID */
	np =3D of_get_cpu_node(cpu, NULL);
	if (np) {
		if (of_property_read_u32(np, "ibm,chip-id", &chip_id) < 0)
			chip_id =3D 0;
	}
=20
Where if np is NULL then we don't initialise chip_id.
=20
Which could be:
=20
	np =3D of_get_cpu_node(cpu, NULL);
        if (of_property_read_u32(np, "ibm,chip-id", &chip_id) < 0)
                chip_id =3D 0;
=20
Because of_property_read_u32() will just return an error if np is NULL.
=20
It's also missing an of_node_put() of np, you should do a separate patch
to fix that. You can just do it unconditionally after the
of_property_read_u32().

I think we can simply get rid of the OF code under xive_native_get_ipi()
and use xc->chip_id instead. It should be safe to use as xive_prepare_cpu=

()=20

should have initialized ->chip_id by the time xive_native_get_ipi() is=20
called.=20

Even better!

cheers

On 08/23/2018 05:24 AM, Michael Ellerman wrote:

Hi Breno,

Breno Leitao [off-list ref] writes:

quoted

Function xive_native_get_ipi() might uses chip_id without it being
initialized. This gives the following error on 'smatch' tool:

	error: uninitialized symbol 'chip_id'

Which is correct, it can be used uninitialised. I'm surprised GCC
doesn't warn about it.

quoted

This patch simply sets chip_id initial value to 0.

I'd prefer we fixed it differently, by explicitly initialising to zero
at the appropriate place in the code.

quoted

diff --git a/arch/powerpc/sysdev/xive/native.c b/arch/powerpc/sysdev/xive/native.c
index 311185b9960a..fc56673a3c0f 100644
--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c

@@ -239,7 +239,7 @@ static bool xive_native_match(struct device_node *node)
 static int xive_native_get_ipi(unsigned int cpu, struct xive_cpu *xc)
 {
 	struct device_node *np;
-	unsigned int chip_id;
+	unsigned int chip_id = 0;
 	s64 irq;
 
 	/* Find the chip ID */

The current code is:

	/* Find the chip ID */
	np = of_get_cpu_node(cpu, NULL);
	if (np) {
		if (of_property_read_u32(np, "ibm,chip-id", &chip_id) < 0)
			chip_id = 0;
	}

Where if np is NULL then we don't initialise chip_id.

Which could be:

	np = of_get_cpu_node(cpu, NULL);
        if (of_property_read_u32(np, "ibm,chip-id", &chip_id) < 0)
                chip_id = 0;

Because of_property_read_u32() will just return an error if np is NULL.

It's also missing an of_node_put() of np, you should do a separate patch
to fix that. You can just do it unconditionally after the
of_property_read_u32().

I think we can simply get rid of the OF code under xive_native_get_ipi()
and use xc->chip_id instead. It should be safe to use as xive_prepare_cpu() 
should have initialized ->chip_id by the time xive_native_get_ipi() is 
called. 

Cheers,

C.

From: Breno Leitao <redacted>

Function xive_native_get_ipi() might uses chip_id without it being
initialized.

This gives the following error on 'smatch' tool:

	error: uninitialized symbol 'chip_id'

The suggestion is using xc->chip_id instead of consulting the OF for chip id,
which is safe since xive_prepare_cpu() should have initialized ->chip_id by
the time xive_native_get_ipi() is called.

CC: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
 arch/powerpc/sysdev/xive/native.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/arch/powerpc/sysdev/xive/native.c b/arch/powerpc/sysdev/xive/native.c
index 311185b9960a..bd90fd464a3a 100644
--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c

@@ -238,20 +238,11 @@ static bool xive_native_match(struct device_node *node)
 #ifdef CONFIG_SMP
 static int xive_native_get_ipi(unsigned int cpu, struct xive_cpu *xc)
 {
-	struct device_node *np;
-	unsigned int chip_id;
 	s64 irq;
 
-	/* Find the chip ID */
-	np = of_get_cpu_node(cpu, NULL);
-	if (np) {
-		if (of_property_read_u32(np, "ibm,chip-id", &chip_id) < 0)
-			chip_id = 0;
-	}
-
 	/* Allocate an IPI and populate info about it */
 	for (;;) {
-		irq = opal_xive_allocate_irq(chip_id);
+		irq = opal_xive_allocate_irq(xc->chip_id);
 		if (irq == OPAL_BUSY) {
 			msleep(1);
 			continue;

-- 
2.17.1

On 08/24/2018 01:26 AM, Breno Leitao wrote:

From: Breno Leitao <redacted>

Function xive_native_get_ipi() might uses chip_id without it being
initialized.

This gives the following error on 'smatch' tool:

	error: uninitialized symbol 'chip_id'

The suggestion is using xc->chip_id instead of consulting the OF for chip id,
which is safe since xive_prepare_cpu() should have initialized ->chip_id by
the time xive_native_get_ipi() is called.

CC: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Breno Leitao <leitao@debian.org>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

Thanks,

C.

On Thu, 2018-08-23 at 23:26:39 UTC, Breno Leitao wrote:

From: Breno Leitao <redacted>

Function xive_native_get_ipi() might uses chip_id without it being
initialized.

This gives the following error on 'smatch' tool:

	error: uninitialized symbol 'chip_id'

The suggestion is using xc->chip_id instead of consulting the OF for chip id,
which is safe since xive_prepare_cpu() should have initialized ->chip_id by
the time xive_native_get_ipi() is called.

CC: C��dric Le Goater <clg@kaod.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: C��dric Le Goater <clg@kaod.org>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/8ac9e5bfd8cf41ef106ac97267117e

cheers