linux-kernel - RE: [PATCH] scsi/mpt2sas: fix unsafe preempt setting for ioc

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Message-ID: <A6888A6805518E4EA4AF7072A28264A6067E89AC2E@inbmail02.lsi.com>
Date:	Tue, 17 Apr 2012 11:25:23 +0530
From:	"Nandigama, Nagalakshmi" <Nagalakshmi.Nandigama@....com>
To:	"Nandigama, Nagalakshmi" <Nagalakshmi.Nandigama@....com>,
	Alex Shi <alex.shi@...el.com>,
	"JBottomley@...allels.com" <JBottomley@...allels.com>
CC:	"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] scsi/mpt2sas: fix unsafe preempt setting for ioc

James,
Request you to reject this patch. 
Instead I posted different patch with subject " [PATCH] [SCSI] mpt2sas : Fix unsafe using smp_processor_id() in preemptible" which will fix this issue.

Regards,
Nagalakshmi

-----Original Message-----
From: linux-scsi-owner@...r.kernel.org [mailto:linux-scsi-owner@...r.kernel.org] On Behalf Of Nandigama, Nagalakshmi
Sent: Tuesday, April 10, 2012 11:27 AM
To: Alex Shi; JBottomley@...allels.com
Cc: linux-scsi@...r.kernel.org; linux-kernel@...r.kernel.org
Subject: RE: [PATCH] scsi/mpt2sas: fix unsafe preempt setting for ioc

This patch seem to be fine. Please consider this patch as Acked-by: "Nandigama, Nagalakshmi" <Nagalakshmi.Nandigama@....com>

Regards,
Nagalakshmi


-----Original Message-----
From: Alex Shi [mailto:alex.shi@...el.com] 
Sent: Monday, March 26, 2012 11:50 AM
To: JBottomley@...allels.com
Cc: Nandigama, Nagalakshmi; linux-scsi@...r.kernel.org; linux-kernel@...r.kernel.org
Subject: [PATCH] scsi/mpt2sas: fix unsafe preempt setting for ioc

commit 911ae943 add a new function:
+_base_get_msix_index(struct MPT2SAS_ADAPTER *ioc)
+{
+       return ioc->cpu_msix_table[smp_processor_id()];
+}
Here smp_processor_id() need be used in preempt safe condition. but
caller did not give this assurance. So fix this in caller.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 drivers/scsi/mpt2sas/mpt2sas_base.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/drivers/scsi/mpt2sas/mpt2sas_base.c b/drivers/scsi/mpt2sas/mpt2sas_base.c
index a78036f..55a368e 100644
--- a/drivers/scsi/mpt2sas/mpt2sas_base.c
+++ b/drivers/scsi/mpt2sas/mpt2sas_base.c
@@ -1803,6 +1803,7 @@ mpt2sas_base_put_smid_scsi_io(struct MPT2SAS_ADAPTER *ioc, u16 smid, u16 handle)
 	u64 *request = (u64 *)&descriptor;
 
 
+	preempt_disable();
 	descriptor.SCSIIO.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_SCSI_IO;
 	descriptor.SCSIIO.MSIxIndex =  _base_get_msix_index(ioc);
 	descriptor.SCSIIO.SMID = cpu_to_le16(smid);
@@ -1810,6 +1811,7 @@ mpt2sas_base_put_smid_scsi_io(struct MPT2SAS_ADAPTER *ioc, u16 smid, u16 handle)
 	descriptor.SCSIIO.LMID = 0;
 	_base_writeq(*request, &ioc->chip->RequestDescriptorPostLow,
 	    &ioc->scsi_lookup_lock);
+	preempt_enable();
 }
 
 
@@ -1849,6 +1851,7 @@ mpt2sas_base_put_smid_default(struct MPT2SAS_ADAPTER *ioc, u16 smid)
 	Mpi2RequestDescriptorUnion_t descriptor;
 	u64 *request = (u64 *)&descriptor;
 
+	preempt_disable();
 	descriptor.Default.RequestFlags = MPI2_REQ_DESCRIPT_FLAGS_DEFAULT_TYPE;
 	descriptor.Default.MSIxIndex =  _base_get_msix_index(ioc);
 	descriptor.Default.SMID = cpu_to_le16(smid);
@@ -1856,6 +1859,7 @@ mpt2sas_base_put_smid_default(struct MPT2SAS_ADAPTER *ioc, u16 smid)
 	descriptor.Default.DescriptorTypeDependent = 0;
 	_base_writeq(*request, &ioc->chip->RequestDescriptorPostLow,
 	    &ioc->scsi_lookup_lock);
+	preempt_enable();
 }
 
 /**
@@ -1873,6 +1877,7 @@ mpt2sas_base_put_smid_target_assist(struct MPT2SAS_ADAPTER *ioc, u16 smid,
 	Mpi2RequestDescriptorUnion_t descriptor;
 	u64 *request = (u64 *)&descriptor;
 
+	preempt_disable();
 	descriptor.SCSITarget.RequestFlags =
 	    MPI2_REQ_DESCRIPT_FLAGS_SCSI_TARGET;
 	descriptor.SCSITarget.MSIxIndex =  _base_get_msix_index(ioc);
@@ -1881,6 +1886,7 @@ mpt2sas_base_put_smid_target_assist(struct MPT2SAS_ADAPTER *ioc, u16 smid,
 	descriptor.SCSITarget.IoIndex = cpu_to_le16(io_index);
 	_base_writeq(*request, &ioc->chip->RequestDescriptorPostLow,
 	    &ioc->scsi_lookup_lock);
+	preempt_enable();
 }
 
 /**
-- 
1.7.5.4

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