Re: [PATCH] scsi/ata: Use unsigned int for cmd's type in ioctls in scsi_host_template

[Bart Van Assche]

On Fri, 2018-10-19 at 10:57 -0700, Nathan Chancellor wrote:
+AD4 Clang warns several times in the scsi subsystem (trimmed for brevity):
+AD4 
+AD4 drivers/scsi/hpsa.c:6209:7: warning: overflow converting case value to
+AD4 switch condition type (2147762695 to 18446744071562347015) +AFs--Wswitch+AF0
+AD4         case CCISS+AF8-GETBUSTYPES:
+AD4              +AF4
+AD4 drivers/scsi/hpsa.c:6208:7: warning: overflow converting case value to
+AD4 switch condition type (2147762694 to 18446744071562347014) +AFs--Wswitch+AF0
+AD4         case CCISS+AF8-GETHEARTBEAT:
+AD4              +AF4
+AD4 
+AD4 The root cause is that the +AF8-IOC macro can generate really large numbers,
+AD4 which don't find into type 'int', which is used for the cmd paremeter in
+AD4 the ioctls in scsi+AF8-host+AF8-template. My research into how GCC and Clang are
+AD4 handling this at a low level didn't prove fruitful. However, looking at
+AD4 the rest of the kernel tree, all ioctls use an 'unsigned int' for the
+AD4 cmd parameter, which will fit all of the +AF8-IOC values in the scsi/ata
+AD4 subsystems.
+AD4 
+AD4 Make that change because none of the ioctls expect to take a negative
+AD4 value, it brings the ioctls inline with the reset of the kernel, and it
+AD4 removes ambiguity, which is never good when dealing with compilers.

Reviewed-by: Bart Van Assche +ADw-bvanassche+AEA-acm.org+AD4