[EXT] Re: [PATCH] rtc: pcf2127: fix uninitialized variable msg

[Biwen Li (OSS)]

> 
> On 09/07/2020 13.38, Biwen Li wrote:
> >>
> >> On 09/07/2020 12.58, Biwen Li wrote:
> >>> From: Biwen Li <biwen.li at nxp.com>
> >>>
> >>> Fix uninitialized variable msg
> >>>
> >>>       struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
> >>> -     struct i2c_msg msg;
> >>> +     struct i2c_msg msg = {0};
> >>>       int ret;
> >>>
> >>>       /* Set the address of the start register to be read */
> >>>
> >>
> >> I assume it's the
> >>
> >>         msg.flags |= I2C_M_RD;
> >>
> >> line that is warned about (please include such info)? Isn't the right
> >> fix to replace that by
> >>
> >>         msg.flags = I2C_M_RD;
> >>
> >> ?
> > Two lines("struct i2c msg;" and "msg.flags |= I2C_M_RD") are warned by
> build system.
> 
> What? That doesn't make sense. Perhaps your compiler is just friendly enough
> to show you the declaration of the struct i2c_msg, but clearly declaring an
> automatic variable without initializing it is not, by itself, wrong. Otherwise "int
> ret;" in that very same function should be warned about, and 100000 other
> instances in any code base written in C.
> 
> Please show the exact output from the compiler and the compiler version.
Sorry, acctually not build system. It's code analysis tool.
Such as:
Declaring variable msg without initializer. (struce i2c_msg msg;)
Uninitialized scalar variable (UNINIT),  uninit_use: Using uninitialized value msg.flags.(msg.flags |= I2C_M_RD)
> 
> > Initializing msg variable will be better.
> 
> No, understanding the cause of the warning and fixing that is clearly better.
> 
> Rasmus