[PATCH] powerpc/mpic: Cleanup irq vector accounting

Available vector space accounts ipis and timer interrupts
while spurious vector was not accounted. Also later
mpic_setup_error_int() escape one more vector, seemingly it
assumes one spurious vector.

Signed-off-by: Bharat Bhushan <redacted>
---
 arch/powerpc/sysdev/fsl_mpic_err.c | 2 +-
 arch/powerpc/sysdev/mpic.c         | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/sysdev/fsl_mpic_err.c b/arch/powerpc/sysdev/fsl_mpic_err.c
index 488ec45..2a98837 100644
--- a/arch/powerpc/sysdev/fsl_mpic_err.c
+++ b/arch/powerpc/sysdev/fsl_mpic_err.c

@@ -76,7 +76,7 @@ int mpic_setup_error_int(struct mpic *mpic, int intvec)
 	mpic->flags |= MPIC_FSL_HAS_EIMR;
 	/* allocate interrupt vectors for error interrupts */
 	for (i = MPIC_MAX_ERR - 1; i >= 0; i--)
-		mpic->err_int_vecs[i] = --intvec;
+		mpic->err_int_vecs[i] = intvec--;
 
 	return 0;
 }

diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 1d4e0ef6..e098d1e 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c

@@ -1380,12 +1380,12 @@ struct mpic * __init mpic_alloc(struct device_node *node,
 		 * global vector number space, as in case of ipis
 		 * and timer interrupts.
 		 *
-		 * Available vector space = intvec_top - 12, where 12
+		 * Available vector space = intvec_top - 13, where 13
 		 * is the number of vectors which have been consumed by
-		 * ipis and timer interrupts.
+		 * ipis, timer interrupts and spurious.
 		 */
 		if (fsl_version >= 0x401) {
-			ret = mpic_setup_error_int(mpic, intvec_top - 12);
+			ret = mpic_setup_error_int(mpic, intvec_top - 13);
 			if (ret)
 				return NULL;
 		}

-- 
1.9.3

Bharat Bhushan [off-list ref] writes:

Available vector space accounts ipis and timer interrupts
while spurious vector was not accounted.

OK. What is the symptom of that? Nothing? Total system crash?

Looks like this can be tagged:

Fixes: 0a4081641d72 ("powerpc/mpic: FSL MPIC error interrupt support.")

Which added the code that uses "12".

Also later
mpic_setup_error_int() escape one more vector, seemingly it
assumes one spurious vector.

Ah right, I get it now.

So there is no bug. It's just a disagreement about whether the "intvec"
argument to mpic_setup_error_int() indicates the first number that's
free to use or the last number that has been allocated.

Right?

cheers

-----Original Message-----
From: Michael Ellerman [mailto:mpe@ellerman.id.au]
Sent: Wednesday, July 4, 2018 6:57 PM
To: Bharat Bhushan <redacted>;
benh@kernel.crashing.org; paulus@samba.org; robh@kernel.org;
geoff@infradead.org; tyreld@linux.vnet.ibm.com; linuxppc-
dev@lists.ozlabs.org; linux-kernel@vger.kernel.org
Cc: Bharat Bhushan <redacted>
Subject: Re: [PATCH] powerpc/mpic: Cleanup irq vector accounting
=20
Bharat Bhushan [off-list ref] writes:
=20

quoted

Available vector space accounts ipis and timer interrupts while
spurious vector was not accounted.

=20
OK. What is the symptom of that? Nothing? Total system crash?
=20
Looks like this can be tagged:
=20
Fixes: 0a4081641d72 ("powerpc/mpic: FSL MPIC error interrupt support.")
=20
Which added the code that uses "12".
=20

quoted

Also later
mpic_setup_error_int() escape one more vector, seemingly it assumes
one spurious vector.

=20
Ah right, I get it now.
=20
So there is no bug. It's just a disagreement about whether the "intvec"
argument to mpic_setup_error_int() indicates the first number that's free=

 to

use or the last number that has been allocated.
=20
Right?

Yes, it is not any bug fix. This is minor cleanup where passing rather than=
 passing "last intvec used" to "intvec to be used" in mpic_setup_error_int(=
).

Thanks
-Bharat

=20
cheers
=20

quoted

Signed-off-by: Bharat Bhushan <redacted>
---
 arch/powerpc/sysdev/fsl_mpic_err.c | 2 +-
 arch/powerpc/sysdev/mpic.c         | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/sysdev/fsl_mpic_err.c

b/arch/powerpc/sysdev/fsl_mpic_err.c
index 488ec45..2a98837 100644

--- a/arch/powerpc/sysdev/fsl_mpic_err.c
+++ b/arch/powerpc/sysdev/fsl_mpic_err.c

@@ -76,7 +76,7 @@ int mpic_setup_error_int(struct mpic *mpic, int

intvec)

quoted

 	mpic->flags |=3D MPIC_FSL_HAS_EIMR;
 	/* allocate interrupt vectors for error interrupts */
 	for (i =3D MPIC_MAX_ERR - 1; i >=3D 0; i--)
-		mpic->err_int_vecs[i] =3D --intvec;
+		mpic->err_int_vecs[i] =3D intvec--;

 	return 0;
 }

diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 1d4e0ef6..e098d1e 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c

@@ -1380,12 +1380,12 @@ struct mpic * __init mpic_alloc(struct

device_node *node,

quoted

 		 * global vector number space, as in case of ipis
 		 * and timer interrupts.
 		 *
-		 * Available vector space =3D intvec_top - 12, where 12
+		 * Available vector space =3D intvec_top - 13, where 13
 		 * is the number of vectors which have been consumed by
-		 * ipis and timer interrupts.
+		 * ipis, timer interrupts and spurious.
 		 */
 		if (fsl_version >=3D 0x401) {
-			ret =3D mpic_setup_error_int(mpic, intvec_top - 12);
+			ret =3D mpic_setup_error_int(mpic, intvec_top - 13);
 			if (ret)
 				return NULL;
 		}
--
1.9.3

On Fri, 2018-06-29 at 10:24:32 UTC, Bharat Bhushan wrote:

Available vector space accounts ipis and timer interrupts
while spurious vector was not accounted. Also later
mpic_setup_error_int() escape one more vector, seemingly it
assumes one spurious vector.

Signed-off-by: Bharat Bhushan <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/fca7bf946e31688edce446fdaa571c

cheers