Re: [Xen-devel] [PATCH] libxl: use llabs() instead abs() for int64_t argument

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Aug 02, 2016 at 06:28:37PM +0100, Andrew Cooper wrote:
> On 02/08/16 18:25, Juergen Gross wrote:
> > Commit 57f8b13c724023c78fa15a80452d1de3e51a1418 ("libxl: memory size
> > in kb requires 64 bit variable") introduced a bug: abs() shouldn't
> > be called with an int64_t argument. llabs() is to be used here.
> 
> Possibly worth identifying that this was caught by a clang build, citing:
> 
> libxl.c:4198:33: error: absolute value function 'abs' given an argument
> of type
>     'int64_t' (aka 'long') but has parameter of type 'int' which may cause
>     truncation of value [-Werror,-Wabsolute-value]
>     if (target_memkb < 0 && abs(target_memkb) > current_target_memkb)
>                                          ^

Juergen, I can fix up the commit message for you, if you don't object to
Andrew's suggestion.

---
Commit 57f8b13c724023c78fa15a80452d1de3e51a1418 ("libxl: memory size
in kb requires 64 bit variable") introduced a bug: abs() shouldn't
be called with an int64_t argument. llabs() is to be used here.

Caught by clang build with error message:

libxl.c:4198:33: error: absolute value function 'abs' given an argument
of type
    'int64_t' (aka 'long') but has parameter of type 'int' which may cause
    truncation of value [-Werror,-Wabsolute-value]
    if (target_memkb < 0 && abs(target_memkb) > current_target_memkb)
---

Wei.

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