Re: [PATCH] sound: pci: emu10k1: code refactoring and casting removal

[Takashi Iwai <tiwai@suse.de>]

At Thu, 17 Oct 2013 08:13:32 -0300,
Geyslan Gregório Bem wrote:
> 
> 2013/10/17 Takashi Iwai <tiwai@suse.de>:
> > At Wed, 16 Oct 2013 19:11:21 -0300,
> > Geyslan G. Bem wrote:
> >>
> >> Partially restructures _snd_emu10k1_audigy_init_efx() and
> >> _snd_emu10k1_init_efx() functions.
> >>
> >> Removes useless casting (void *) from value returned by kcalloc;
> >> see Documentation/CodingStyle, Chap 14.
> >>
> >> Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
> >> ---
> >>  sound/pci/emu10k1/emufx.c | 84 ++++++++++++++++++++++++++---------------------
> >>  1 file changed, 46 insertions(+), 38 deletions(-)
> >>
> >> diff --git a/sound/pci/emu10k1/emufx.c b/sound/pci/emu10k1/emufx.c
> >> index 0275209..afd4691 100644
> >> --- a/sound/pci/emu10k1/emufx.c
> >> +++ b/sound/pci/emu10k1/emufx.c
> >> @@ -1182,15 +1182,20 @@ static int _snd_emu10k1_audigy_init_efx(struct snd_emu10k1 *emu)
> >>       u32 *gpr_map;
> >>       mm_segment_t seg;
> >>
> >> -     if ((icode = kzalloc(sizeof(*icode), GFP_KERNEL)) == NULL ||
> >> -         (icode->gpr_map = (u_int32_t __user *)
> >> -          kcalloc(512 + 256 + 256 + 2 * 1024, sizeof(u_int32_t),
> >> -                  GFP_KERNEL)) == NULL ||
> >> -         (controls = kcalloc(SND_EMU10K1_GPR_CONTROLS,
> >> -                             sizeof(*controls), GFP_KERNEL)) == NULL) {
> >> -             err = -ENOMEM;
> >> -             goto __err;
> >> -     }
> >> +     err = -ENOMEM;
> >> +     icode = kzalloc(sizeof(*icode), GFP_KERNEL);
> >> +     if (!icode)
> >> +             return err;
> >> +
> >> +     icode->gpr_map = (__user) kcalloc(512 + 256 + 256 + 2 * 1024,
> >> +                                       sizeof(u_int32_t), GFP_KERNEL);
> >> +     if (!icode->gpr_map)
> >> +             goto __err_gpr;
> >> +     controls = kcalloc(SND_EMU10K1_GPR_CONTROLS,
> >> +                        sizeof(*controls), GFP_KERNEL);
> >> +     if (!controls)
> >> +             goto __err_ctrls;
> >> +
> >>       gpr_map = (u32 __force *)icode->gpr_map;
> >>
> >>       icode->tram_data_map = icode->gpr_map + 512;
> >> @@ -1741,12 +1746,12 @@ A_OP(icode, &ptr, iMAC0, A_GPR(var), A_GPR(var), A_GPR(vol), A_EXTIN(input))
> >>       emu->support_tlv = 0; /* clear again */
> >>       snd_leave_user(seg);
> >>
> >> - __err:
> >> +__err:
> >>       kfree(controls);
> >> -     if (icode != NULL) {
> >> -             kfree((void __force *)icode->gpr_map);
> >> -             kfree(icode);
> >> -     }
> >> +__err_ctrls:
> >> +     kfree((void __force *)icode->gpr_map);
> >> +__err_gpr:
> >> +     kfree(icode);
> >>       return err;
> >>  }
> >>
> >> @@ -1813,18 +1818,26 @@ static int _snd_emu10k1_init_efx(struct snd_emu10k1 *emu)
> >>       u32 *gpr_map;
> >>       mm_segment_t seg;
> >>
> >> -     if ((icode = kzalloc(sizeof(*icode), GFP_KERNEL)) == NULL)
> >> -             return -ENOMEM;
> >> -     if ((icode->gpr_map = (u_int32_t __user *)
> >> -          kcalloc(256 + 160 + 160 + 2 * 512, sizeof(u_int32_t),
> >> -                  GFP_KERNEL)) == NULL ||
> >> -            (controls = kcalloc(SND_EMU10K1_GPR_CONTROLS,
> >> -                             sizeof(struct snd_emu10k1_fx8010_control_gpr),
> >> -                             GFP_KERNEL)) == NULL ||
> >> -         (ipcm = kzalloc(sizeof(*ipcm), GFP_KERNEL)) == NULL) {
> >> -             err = -ENOMEM;
> >> -             goto __err;
> >> -     }
> >> +     err = -ENOMEM;
> >> +     icode = kzalloc(sizeof(*icode), GFP_KERNEL);
> >> +     if (!icode)
> >> +             return err;
> >> +
> >> +     icode->gpr_map = (__user) kcalloc(256 + 160 + 160 + 2 * 512,
> >> +                                       sizeof(u_int32_t), GFP_KERNEL);
> >> +     if (!icode->gpr_map)
> >> +             goto __err_gpr;
> >> +
> >> +     controls = kcalloc(SND_EMU10K1_GPR_CONTROLS,
> >> +                        sizeof(struct snd_emu10k1_fx8010_control_gpr),
> >> +                        GFP_KERNEL);
> >> +     if (!controls)
> >> +             goto __err_ctrls;
> >> +
> >> +     ipcm = kzalloc(sizeof(*ipcm), GFP_KERNEL);
> >> +     if (!ipcm)
> >> +             goto __err_ipcm;
> >> +
> >>       gpr_map = (u32 __force *)icode->gpr_map;
> >>
> >>       icode->tram_data_map = icode->gpr_map + 256;
> >> @@ -2335,14 +2348,8 @@ static int _snd_emu10k1_init_efx(struct snd_emu10k1 *emu)
> >>               for (z = 0; z < 16; z++)
> >>                       OP(icode, &ptr, iACC3, FXBUS2(z), C_00000000, C_00000000, EXTIN(z));
> >>       }
> >> -
> >>
> >> -     if (gpr > tmp) {
> >> -             snd_BUG();
> >> -             err = -EIO;
> >> -             goto __err;
> >> -     }
> >> -     if (i > SND_EMU10K1_GPR_CONTROLS) {
> >> +     if (gpr > tmp || i > SND_EMU10K1_GPR_CONTROLS) {
> >>               snd_BUG();
> >
> > In that way, you can't distinguish which condition triggered the bug
> > (it could be shown in WARN() called in snd_BUG() in the original
> > version), so this is a functional change.  Avoid it in a clean up
> > patch.
> >
> >
> > thanks,
> >
> > Takashi
> 
> Takashi, I actually thought that that change was a cleanup.  :) But
> ok, now I see the reason (tracing)
> What about using this instead snd_BUG?
> 
> snd_printd(KERN_WARN "BUG?\ngpr: %d, i: %d", gpr, i);
> 
> It prints file, line and we can put the data. I really want to reduce
> repeated code.

WARN() gives more precise information.

Geyslan, you don't have to waste too much of your time (and my time
for review) for this kind of so old driver code unless it really fixes
the bugs.  A clean up is good in general, but it can be sometimes
worse than nothing since it also breaks the history, thus makes hard
to follow via "git blame", for example, and of course, there is always
a potential danger of regression.

So, if it's about clean up, do it only in a systematic way that others
can follow easily, and don't do it too intensively.


thanks,

Takashi