| Message ID | 20190322143431.1235295-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: davinci-isif: avoid uninitialized variable use | expand |
On Fri, Mar 22, 2019 at 03:34:22PM +0100, Arnd Bergmann wrote: > clang warns about a possible variable use that gcc never > complained about: > > drivers/media/platform/davinci/isif.c:982:32: error: variable 'frame_size' is uninitialized when used here > [-Werror,-Wuninitialized] > dm365_vpss_set_pg_frame_size(frame_size); > ^~~~~~~~~~ > drivers/media/platform/davinci/isif.c:887:2: note: variable 'frame_size' is declared here > struct vpss_pg_frame_size frame_size; > ^ > 1 error generated. > > There is no initialization for this variable at all, and there > has never been one in the mainline kernel, so we really should > not put that stack data into an mmio register. > > On the other hand, I suspect that gcc checks the condition > more closely and notices that the global > isif_cfg.bayer.config_params.test_pat_gen flag is initialized > to zero and never written to from any code path, so anything > depending on it can be eliminated. > > To shut up the clang warning, just remove the dead code manually, > it has probably never been used because any attempt to do so > would have resulted in undefined behavior. > > Fixes: 63e3ab142fa3 ("V4L/DVB: V4L - vpfe capture - source for ISIF driver on DM365") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > --- > drivers/media/platform/davinci/isif.c | 9 --------- > 1 file changed, 9 deletions(-) > > diff --git a/drivers/media/platform/davinci/isif.c b/drivers/media/platform/davinci/isif.c > index 47cecd10eb9f..2dee9af6d413 100644 > --- a/drivers/media/platform/davinci/isif.c > +++ b/drivers/media/platform/davinci/isif.c > @@ -884,9 +884,7 @@ static int isif_set_hw_if_params(struct vpfe_hw_if_param *params) > static int isif_config_ycbcr(void) > { > struct isif_ycbcr_config *params = &isif_cfg.ycbcr; > - struct vpss_pg_frame_size frame_size; > u32 modeset = 0, ccdcfg = 0; > - struct vpss_sync_pol sync; > > dev_dbg(isif_cfg.dev, "\nStarting isif_config_ycbcr..."); > > @@ -974,13 +972,6 @@ static int isif_config_ycbcr(void) > /* two fields are interleaved in memory */ > regw(0x00000249, SDOFST); > > - /* Setup test pattern if enabled */ > - if (isif_cfg.bayer.config_params.test_pat_gen) { > - sync.ccdpg_hdpol = params->hd_pol; > - sync.ccdpg_vdpol = params->vd_pol; > - dm365_vpss_set_sync_pol(sync); > - dm365_vpss_set_pg_frame_size(frame_size); > - } > return 0; > } > > -- > 2.20.0 >
On Fri, Mar 22, 2019 at 2:34 PM Arnd Bergmann <arnd@arndb.de> wrote: > > clang warns about a possible variable use that gcc never > complained about: > > drivers/media/platform/davinci/isif.c:982:32: error: variable 'frame_size' is uninitialized when used here > [-Werror,-Wuninitialized] > dm365_vpss_set_pg_frame_size(frame_size); > ^~~~~~~~~~ > drivers/media/platform/davinci/isif.c:887:2: note: variable 'frame_size' is declared here > struct vpss_pg_frame_size frame_size; > ^ > 1 error generated. > > There is no initialization for this variable at all, and there > has never been one in the mainline kernel, so we really should > not put that stack data into an mmio register. > > On the other hand, I suspect that gcc checks the condition > more closely and notices that the global > isif_cfg.bayer.config_params.test_pat_gen flag is initialized > to zero and never written to from any code path, so anything > depending on it can be eliminated. > > To shut up the clang warning, just remove the dead code manually, > it has probably never been used because any attempt to do so > would have resulted in undefined behavior. > > Fixes: 63e3ab142fa3 ("V4L/DVB: V4L - vpfe capture - source for ISIF driver on DM365") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/media/platform/davinci/isif.c | 9 --------- > 1 file changed, 9 deletions(-) > Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com> Cheers, --Prabhakar Lad > diff --git a/drivers/media/platform/davinci/isif.c b/drivers/media/platform/davinci/isif.c > index 47cecd10eb9f..2dee9af6d413 100644 > --- a/drivers/media/platform/davinci/isif.c > +++ b/drivers/media/platform/davinci/isif.c > @@ -884,9 +884,7 @@ static int isif_set_hw_if_params(struct vpfe_hw_if_param *params) > static int isif_config_ycbcr(void) > { > struct isif_ycbcr_config *params = &isif_cfg.ycbcr; > - struct vpss_pg_frame_size frame_size; > u32 modeset = 0, ccdcfg = 0; > - struct vpss_sync_pol sync; > > dev_dbg(isif_cfg.dev, "\nStarting isif_config_ycbcr..."); > > @@ -974,13 +972,6 @@ static int isif_config_ycbcr(void) > /* two fields are interleaved in memory */ > regw(0x00000249, SDOFST); > > - /* Setup test pattern if enabled */ > - if (isif_cfg.bayer.config_params.test_pat_gen) { > - sync.ccdpg_hdpol = params->hd_pol; > - sync.ccdpg_vdpol = params->vd_pol; > - dm365_vpss_set_sync_pol(sync); > - dm365_vpss_set_pg_frame_size(frame_size); > - } > return 0; > } > > -- > 2.20.0 >
diff --git a/drivers/media/platform/davinci/isif.c b/drivers/media/platform/davinci/isif.c index 47cecd10eb9f..2dee9af6d413 100644 --- a/drivers/media/platform/davinci/isif.c +++ b/drivers/media/platform/davinci/isif.c @@ -884,9 +884,7 @@ static int isif_set_hw_if_params(struct vpfe_hw_if_param *params) static int isif_config_ycbcr(void) { struct isif_ycbcr_config *params = &isif_cfg.ycbcr; - struct vpss_pg_frame_size frame_size; u32 modeset = 0, ccdcfg = 0; - struct vpss_sync_pol sync; dev_dbg(isif_cfg.dev, "\nStarting isif_config_ycbcr..."); @@ -974,13 +972,6 @@ static int isif_config_ycbcr(void) /* two fields are interleaved in memory */ regw(0x00000249, SDOFST); - /* Setup test pattern if enabled */ - if (isif_cfg.bayer.config_params.test_pat_gen) { - sync.ccdpg_hdpol = params->hd_pol; - sync.ccdpg_vdpol = params->vd_pol; - dm365_vpss_set_sync_pol(sync); - dm365_vpss_set_pg_frame_size(frame_size); - } return 0; }
clang warns about a possible variable use that gcc never complained about: drivers/media/platform/davinci/isif.c:982:32: error: variable 'frame_size' is uninitialized when used here [-Werror,-Wuninitialized] dm365_vpss_set_pg_frame_size(frame_size); ^~~~~~~~~~ drivers/media/platform/davinci/isif.c:887:2: note: variable 'frame_size' is declared here struct vpss_pg_frame_size frame_size; ^ 1 error generated. There is no initialization for this variable at all, and there has never been one in the mainline kernel, so we really should not put that stack data into an mmio register. On the other hand, I suspect that gcc checks the condition more closely and notices that the global isif_cfg.bayer.config_params.test_pat_gen flag is initialized to zero and never written to from any code path, so anything depending on it can be eliminated. To shut up the clang warning, just remove the dead code manually, it has probably never been used because any attempt to do so would have resulted in undefined behavior. Fixes: 63e3ab142fa3 ("V4L/DVB: V4L - vpfe capture - source for ISIF driver on DM365") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/media/platform/davinci/isif.c | 9 --------- 1 file changed, 9 deletions(-)