| Message ID | 20210225150119.405469-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/amd/display: Fix an uninitialized index variable | expand |
On Thu, Feb 25, 2021 at 7:01 AM Arnd Bergmann <arnd@kernel.org> wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > clang points out that the new logic uses an always-uninitialized > array index: > > drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9810:38: warning: variable 'i' is uninitialized when used here [-Wuninitialized] > timing = &edid->detailed_timings[i]; > ^ > drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9720:7: note: initialize the variable 'i' to silence this warning > > My best guess is that the index should have been returned by the > parse_hdmi_amd_vsdb() function that walks an array here, so do that. > > Fixes: f9b4f20c4777 ("drm/amd/display: Add Freesync HDMI support to DM") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index b19b93c74bae..667c0d52dbfa 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -9736,7 +9736,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector, > return false; > } > > -static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > +static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info) > { > uint8_t *edid_ext = NULL; > @@ -9746,7 +9746,7 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > /*----- drm_find_cea_extension() -----*/ > /* No EDID or EDID extensions */ > if (edid == NULL || edid->extensions == 0) > - return false; > + return -ENODEV; > > /* Find CEA extension */ > for (i = 0; i < edid->extensions; i++) { > @@ -9756,14 +9756,15 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > } > > if (i == edid->extensions) > - return false; > + return -ENODEV; > > /*----- cea_db_offsets() -----*/ > if (edid_ext[0] != CEA_EXT) > - return false; > + return -ENODEV; > > valid_vsdb_found = parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info); > - return valid_vsdb_found; > + > + return valid_vsdb_found ? i : -ENODEV; Thanks for the patch! I don't think we need a local variable to store the return value from one function call that's immediately returned, ie. return parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info) ? i : -ENODEV; would suffice, but the patch is still fine as is. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > } > > void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > @@ -9781,7 +9782,6 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > struct amdgpu_device *adev = drm_to_adev(dev); > bool freesync_capable = false; > struct amdgpu_hdmi_vsdb_info vsdb_info = {0}; > - bool hdmi_valid_vsdb_found = false; > > if (!connector->state) { > DRM_ERROR("%s - Connector has no state", __func__); > @@ -9857,8 +9857,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > } > } > } else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) { > - hdmi_valid_vsdb_found = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > - if (hdmi_valid_vsdb_found && vsdb_info.freesync_supported) { > + i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > + if (i >= 0 && vsdb_info.freesync_supported) { reusing `i` here is safe, for now, but reuse of variables like this in separate branches like this might not get noticed if the function is amended in the future. > timing = &edid->detailed_timings[i]; > data = &timing->data.other_data; > > -- > 2.29.2 >
On Thu, Feb 25, 2021 at 10:34 PM 'Nick Desaulniers' via Clang Built Linux <clang-built-linux@googlegroups.com> wrote: > return parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info) ? i : -ENODEV; > > would suffice, but the patch is still fine as is. Right, I did not want to change more than necessary here, and the original code already had the extra assignment instead of returning the value. > > @@ -9857,8 +9857,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > > } > > } > > } else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) { > > - hdmi_valid_vsdb_found = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > > - if (hdmi_valid_vsdb_found && vsdb_info.freesync_supported) { > > + i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > > + if (i >= 0 && vsdb_info.freesync_supported) { > > reusing `i` here is safe, for now, but reuse of variables like this in > separate branches like this might not get noticed if the function is > amended in the future. > > > timing = &edid->detailed_timings[i]; > > data = &timing->data.other_data; The entire point of the patch is that 'i' is in fact used in the following line, but was lacking an intialization. Arnd
On Thu, Feb 25, 2021 at 10:01 AM Arnd Bergmann <arnd@kernel.org> wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > clang points out that the new logic uses an always-uninitialized > array index: > > drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9810:38: warning: variable 'i' is uninitialized when used here [-Wuninitialized] > timing = &edid->detailed_timings[i]; > ^ > drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9720:7: note: initialize the variable 'i' to silence this warning > > My best guess is that the index should have been returned by the > parse_hdmi_amd_vsdb() function that walks an array here, so do that. > > Fixes: f9b4f20c4777 ("drm/amd/display: Add Freesync HDMI support to DM") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> This looks correct to me. Stylon can you verify? Thanks, Alex > --- > .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index b19b93c74bae..667c0d52dbfa 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -9736,7 +9736,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector, > return false; > } > > -static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > +static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info) > { > uint8_t *edid_ext = NULL; > @@ -9746,7 +9746,7 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > /*----- drm_find_cea_extension() -----*/ > /* No EDID or EDID extensions */ > if (edid == NULL || edid->extensions == 0) > - return false; > + return -ENODEV; > > /* Find CEA extension */ > for (i = 0; i < edid->extensions; i++) { > @@ -9756,14 +9756,15 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > } > > if (i == edid->extensions) > - return false; > + return -ENODEV; > > /*----- cea_db_offsets() -----*/ > if (edid_ext[0] != CEA_EXT) > - return false; > + return -ENODEV; > > valid_vsdb_found = parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info); > - return valid_vsdb_found; > + > + return valid_vsdb_found ? i : -ENODEV; > } > > void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > @@ -9781,7 +9782,6 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > struct amdgpu_device *adev = drm_to_adev(dev); > bool freesync_capable = false; > struct amdgpu_hdmi_vsdb_info vsdb_info = {0}; > - bool hdmi_valid_vsdb_found = false; > > if (!connector->state) { > DRM_ERROR("%s - Connector has no state", __func__); > @@ -9857,8 +9857,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > } > } > } else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) { > - hdmi_valid_vsdb_found = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > - if (hdmi_valid_vsdb_found && vsdb_info.freesync_supported) { > + i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > + if (i >= 0 && vsdb_info.freesync_supported) { > timing = &edid->detailed_timings[i]; > data = &timing->data.other_data; > > -- > 2.29.2 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
On Thu, Feb 25, 2021 at 10:01 AM Arnd Bergmann <arnd@kernel.org> wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > clang points out that the new logic uses an always-uninitialized > array index: > > drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9810:38: warning: variable 'i' is uninitialized when used here [-Wuninitialized] > timing = &edid->detailed_timings[i]; > ^ > drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:9720:7: note: initialize the variable 'i' to silence this warning > > My best guess is that the index should have been returned by the > parse_hdmi_amd_vsdb() function that walks an array here, so do that. > > Fixes: f9b4f20c4777 ("drm/amd/display: Add Freesync HDMI support to DM") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Applied. Thanks! Alex > --- > .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index b19b93c74bae..667c0d52dbfa 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -9736,7 +9736,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector, > return false; > } > > -static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > +static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info) > { > uint8_t *edid_ext = NULL; > @@ -9746,7 +9746,7 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > /*----- drm_find_cea_extension() -----*/ > /* No EDID or EDID extensions */ > if (edid == NULL || edid->extensions == 0) > - return false; > + return -ENODEV; > > /* Find CEA extension */ > for (i = 0; i < edid->extensions; i++) { > @@ -9756,14 +9756,15 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, > } > > if (i == edid->extensions) > - return false; > + return -ENODEV; > > /*----- cea_db_offsets() -----*/ > if (edid_ext[0] != CEA_EXT) > - return false; > + return -ENODEV; > > valid_vsdb_found = parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info); > - return valid_vsdb_found; > + > + return valid_vsdb_found ? i : -ENODEV; > } > > void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > @@ -9781,7 +9782,6 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > struct amdgpu_device *adev = drm_to_adev(dev); > bool freesync_capable = false; > struct amdgpu_hdmi_vsdb_info vsdb_info = {0}; > - bool hdmi_valid_vsdb_found = false; > > if (!connector->state) { > DRM_ERROR("%s - Connector has no state", __func__); > @@ -9857,8 +9857,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, > } > } > } else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) { > - hdmi_valid_vsdb_found = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > - if (hdmi_valid_vsdb_found && vsdb_info.freesync_supported) { > + i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); > + if (i >= 0 && vsdb_info.freesync_supported) { > timing = &edid->detailed_timings[i]; > data = &timing->data.other_data; > > -- > 2.29.2 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index b19b93c74bae..667c0d52dbfa 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -9736,7 +9736,7 @@ static bool parse_edid_cea(struct amdgpu_dm_connector *aconnector, return false; } -static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, +static int parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, struct edid *edid, struct amdgpu_hdmi_vsdb_info *vsdb_info) { uint8_t *edid_ext = NULL; @@ -9746,7 +9746,7 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, /*----- drm_find_cea_extension() -----*/ /* No EDID or EDID extensions */ if (edid == NULL || edid->extensions == 0) - return false; + return -ENODEV; /* Find CEA extension */ for (i = 0; i < edid->extensions; i++) { @@ -9756,14 +9756,15 @@ static bool parse_hdmi_amd_vsdb(struct amdgpu_dm_connector *aconnector, } if (i == edid->extensions) - return false; + return -ENODEV; /*----- cea_db_offsets() -----*/ if (edid_ext[0] != CEA_EXT) - return false; + return -ENODEV; valid_vsdb_found = parse_edid_cea(aconnector, edid_ext, EDID_LENGTH, vsdb_info); - return valid_vsdb_found; + + return valid_vsdb_found ? i : -ENODEV; } void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, @@ -9781,7 +9782,6 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, struct amdgpu_device *adev = drm_to_adev(dev); bool freesync_capable = false; struct amdgpu_hdmi_vsdb_info vsdb_info = {0}; - bool hdmi_valid_vsdb_found = false; if (!connector->state) { DRM_ERROR("%s - Connector has no state", __func__); @@ -9857,8 +9857,8 @@ void amdgpu_dm_update_freesync_caps(struct drm_connector *connector, } } } else if (edid && amdgpu_dm_connector->dc_sink->sink_signal == SIGNAL_TYPE_HDMI_TYPE_A) { - hdmi_valid_vsdb_found = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); - if (hdmi_valid_vsdb_found && vsdb_info.freesync_supported) { + i = parse_hdmi_amd_vsdb(amdgpu_dm_connector, edid, &vsdb_info); + if (i >= 0 && vsdb_info.freesync_supported) { timing = &edid->detailed_timings[i]; data = &timing->data.other_data;