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Subject: RE: [PATCH v4] scsi/ata: Use unsigned int for cmd's type in ioctls in
 scsi_host_template
Thread-Topic: [PATCH v4] scsi/ata: Use unsigned int for cmd's type in ioctls
 in scsi_host_template
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Date:   Mon, 28 Jan 2019 16:16:34 +0000
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Clang warns several times in the scsi subsystem (trimmed for brevity):

drivers/scsi/hpsa.c:6209:7: warning: overflow converting case value to swit=
ch condition type (2147762695 to 18446744071562347015) [-Wswitch]
        case CCISS_GETBUSTYPES:
             ^
drivers/scsi/hpsa.c:6208:7: warning: overflow converting case value to swit=
ch condition type (2147762694 to 18446744071562347014) [-Wswitch]
        case CCISS_GETHEARTBEAT:
             ^

The root cause is that the _IOC macro can generate really large numbers, wh=
ich don't find into type 'int', which is used for the cmd paremeter in the =
ioctls in scsi_host_template. My research into how GCC and Clang are handli=
ng this at a low level didn't prove fruitful. However, looking at the rest =
of the kernel tree, all ioctls use an 'unsigned int' for the cmd parameter,=
 which will fit all of the _IOC values in the scsi/ata subsystems.

Make that change because none of the ioctls expect to take a negative value=
, it brings the ioctls inline with the reset of the kernel, and it removes =
ambiguity, which is never good when dealing with compilers.

Link: https://github.com/ClangBuiltLinux/linux/issues/85
Link: https://github.com/ClangBuiltLinux/linux/issues/154
Link: https://github.com/ClangBuiltLinux/linux/issues/157
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>

 static void __exit esas2r_exit(void)
diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c index ff67ef5d5347..=
28cfd3d01c5a 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -251,10 +251,11 @@ static int number_of_controllers;

Acked-by: Don Brace <don.brace@microsemi.com>

=20
diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/=
smartpqi_init.c
index f564af8949e8..5d9ccbab7581 100644
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -6043,7 +6043,8 @@ static int pqi_passthru_ioctl(struct pqi_ctrl_info *c=
trl_info, void __user *arg)
 	return rc;
 }

Acked-by: Don Brace <don.brace@microsemi.com>
=20