| Message ID | 1447946528-1533-5-git-send-email-eric.auger@linaro.org |
|---|---|
| State | New |
| Headers | show |
Eric Auger <eric.auger@linaro.org> writes: > Current qemu_fdt_getprop exits if the property is not found. It is > sometimes needed to read an optional property, in which case we do > not wish to exit but simply returns a null value. > > This is what this new qemu_fdt_getprop_optional function does. > > Signed-off-by: Eric Auger <eric.auger@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > --- > device_tree.c | 17 +++++++++++++++++ > include/sysemu/device_tree.h | 2 ++ > 2 files changed, 19 insertions(+) > > diff --git a/device_tree.c b/device_tree.c > index f184e3c..a318683 100644 > --- a/device_tree.c > +++ b/device_tree.c > @@ -280,6 +280,23 @@ const void *qemu_fdt_getprop(void *fdt, const char *node_path, > return r; > } > > +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, > + const char *property, bool optional, int *lenp) > +{ > + int len; > + const void *r; > + if (!lenp) { > + lenp = &len; > + } > + r = fdt_getprop(fdt, findnode_nofail(fdt, node_path), property, lenp); > + if (!r && !optional) { > + error_report("%s: Couldn't get %s/%s: %s", __func__, > + node_path, property, fdt_strerror(*lenp)); > + exit(1); > + } > + return r; > +} > + > uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, > const char *property) > { > diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h > index f9e6e6e..10cbe8e 100644 > --- a/include/sysemu/device_tree.h > +++ b/include/sysemu/device_tree.h > @@ -34,6 +34,8 @@ int qemu_fdt_setprop_phandle(void *fdt, const char *node_path, > const char *target_node_path); > const void *qemu_fdt_getprop(void *fdt, const char *node_path, > const char *property, int *lenp); > +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, > + const char *property, bool optional, int *lenp); > uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, > const char *property); > uint32_t qemu_fdt_get_phandle(void *fdt, const char *path); -- Alex Bennée
On Thu, Nov 19, 2015 at 7:22 AM, Eric Auger <eric.auger@linaro.org> wrote: > Current qemu_fdt_getprop exits if the property is not found. It is > sometimes needed to read an optional property, in which case we do > not wish to exit but simply returns a null value. > > This is what this new qemu_fdt_getprop_optional function does. > > Signed-off-by: Eric Auger <eric.auger@linaro.org> > --- > device_tree.c | 17 +++++++++++++++++ > include/sysemu/device_tree.h | 2 ++ > 2 files changed, 19 insertions(+) > > diff --git a/device_tree.c b/device_tree.c > index f184e3c..a318683 100644 > --- a/device_tree.c > +++ b/device_tree.c > @@ -280,6 +280,23 @@ const void *qemu_fdt_getprop(void *fdt, const char *node_path, > return r; > } > > +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, > + const char *property, bool optional, int *lenp) > +{ > + int len; > + const void *r; > + if (!lenp) { > + lenp = &len; > + } > + r = fdt_getprop(fdt, findnode_nofail(fdt, node_path), property, lenp); > + if (!r && !optional) { > + error_report("%s: Couldn't get %s/%s: %s", __func__, > + node_path, property, fdt_strerror(*lenp)); > + exit(1); > + } > + return r; > +} > + The real problem here is that the device-tree API is self-asserting. This looks the old _nofail system that we removed but just named in reverse. The correct solution here is to use the Error API properly. Convert qemu_fdt_getprop to accept an Error **, and all existing users are converted to pass &error_fatal. This will preserve existing behaviour. Then to use the API with your optional semantic your pass NULL for the Error **. Regards, Peter > uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, > const char *property) > { > diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h > index f9e6e6e..10cbe8e 100644 > --- a/include/sysemu/device_tree.h > +++ b/include/sysemu/device_tree.h > @@ -34,6 +34,8 @@ int qemu_fdt_setprop_phandle(void *fdt, const char *node_path, > const char *target_node_path); > const void *qemu_fdt_getprop(void *fdt, const char *node_path, > const char *property, int *lenp); > +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, > + const char *property, bool optional, int *lenp); > uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, > const char *property); > uint32_t qemu_fdt_get_phandle(void *fdt, const char *path); > -- > 1.8.3.2 > >
Hi Peter, On 11/27/2015 08:38 PM, Peter Crosthwaite wrote: > On Thu, Nov 19, 2015 at 7:22 AM, Eric Auger <eric.auger@linaro.org> wrote: >> Current qemu_fdt_getprop exits if the property is not found. It is >> sometimes needed to read an optional property, in which case we do >> not wish to exit but simply returns a null value. >> >> This is what this new qemu_fdt_getprop_optional function does. >> >> Signed-off-by: Eric Auger <eric.auger@linaro.org> >> --- >> device_tree.c | 17 +++++++++++++++++ >> include/sysemu/device_tree.h | 2 ++ >> 2 files changed, 19 insertions(+) >> >> diff --git a/device_tree.c b/device_tree.c >> index f184e3c..a318683 100644 >> --- a/device_tree.c >> +++ b/device_tree.c >> @@ -280,6 +280,23 @@ const void *qemu_fdt_getprop(void *fdt, const char *node_path, >> return r; >> } >> >> +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, >> + const char *property, bool optional, int *lenp) >> +{ >> + int len; >> + const void *r; >> + if (!lenp) { >> + lenp = &len; >> + } >> + r = fdt_getprop(fdt, findnode_nofail(fdt, node_path), property, lenp); >> + if (!r && !optional) { >> + error_report("%s: Couldn't get %s/%s: %s", __func__, >> + node_path, property, fdt_strerror(*lenp)); >> + exit(1); >> + } >> + return r; >> +} >> + > > The real problem here is that the device-tree API is self-asserting. > This looks the old _nofail system that we removed but just named in > reverse. The correct solution here is to use the Error API properly. > Convert qemu_fdt_getprop to accept an Error **, and all existing users > are converted to pass &error_fatal. This will preserve existing > behaviour. Then to use the API with your optional semantic your pass > NULL for the Error **. OK I will implement your proposal. Thanks for your time. Best Regards Eric > > Regards, > Peter > >> uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, >> const char *property) >> { >> diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h >> index f9e6e6e..10cbe8e 100644 >> --- a/include/sysemu/device_tree.h >> +++ b/include/sysemu/device_tree.h >> @@ -34,6 +34,8 @@ int qemu_fdt_setprop_phandle(void *fdt, const char *node_path, >> const char *target_node_path); >> const void *qemu_fdt_getprop(void *fdt, const char *node_path, >> const char *property, int *lenp); >> +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, >> + const char *property, bool optional, int *lenp); >> uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, >> const char *property); >> uint32_t qemu_fdt_get_phandle(void *fdt, const char *path); >> -- >> 1.8.3.2 >> >>
diff --git a/device_tree.c b/device_tree.c index f184e3c..a318683 100644 --- a/device_tree.c +++ b/device_tree.c @@ -280,6 +280,23 @@ const void *qemu_fdt_getprop(void *fdt, const char *node_path, return r; } +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, + const char *property, bool optional, int *lenp) +{ + int len; + const void *r; + if (!lenp) { + lenp = &len; + } + r = fdt_getprop(fdt, findnode_nofail(fdt, node_path), property, lenp); + if (!r && !optional) { + error_report("%s: Couldn't get %s/%s: %s", __func__, + node_path, property, fdt_strerror(*lenp)); + exit(1); + } + return r; +} + uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, const char *property) { diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h index f9e6e6e..10cbe8e 100644 --- a/include/sysemu/device_tree.h +++ b/include/sysemu/device_tree.h @@ -34,6 +34,8 @@ int qemu_fdt_setprop_phandle(void *fdt, const char *node_path, const char *target_node_path); const void *qemu_fdt_getprop(void *fdt, const char *node_path, const char *property, int *lenp); +const void *qemu_fdt_getprop_optional(void *fdt, const char *node_path, + const char *property, bool optional, int *lenp); uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path, const char *property); uint32_t qemu_fdt_get_phandle(void *fdt, const char *path);
Current qemu_fdt_getprop exits if the property is not found. It is sometimes needed to read an optional property, in which case we do not wish to exit but simply returns a null value. This is what this new qemu_fdt_getprop_optional function does. Signed-off-by: Eric Auger <eric.auger@linaro.org> --- device_tree.c | 17 +++++++++++++++++ include/sysemu/device_tree.h | 2 ++ 2 files changed, 19 insertions(+)