| Message ID | 20220308123712.18613-1-andriy.shevchenko@linux.intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v4,1/1] device property: Allow error pointer to be passed to fwnode APIs | expand |
Hi Andy, > Some of the fwnode APIs might return an error pointer instead of NULL > or valid fwnode handle. The result of such API call may be considered > optional and hence the test for it is usually done in a form of > > fwnode = fwnode_find_reference(...); > if (IS_ERR(fwnode)) > ...error handling... > > Nevertheless the resulting fwnode may have bumped the reference count > and hence caller of the above API is obliged to call fwnode_handle_put(). > Since fwnode may be not valid either as NULL or error pointer the check > has to be performed there. This approach uglifies the code and adds > a point of making a mistake, i.e. forgetting about error point case. > > To prevent this, allow an error pointer to be passed to the fwnode APIs. > > Fixes: 83b34afb6b79 ("device property: Introduce fwnode_find_reference()") > Reported-by: Nuno Sá <nuno.sa@analog.com> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Tested-by: Nuno Sá <nuno.sa@analog.com> > Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com> > Acked-by: Nuno Sá <nuno.sa@analog.com> This breaks SFP/phylink (using the lan966x switch) on my board. See below for more details. [..] > @@ -480,15 +485,16 @@ int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode, > { > int ret; > > + if (IS_ERR_OR_NULL(fwnode)) > + return -ENOENT; > + > ret = fwnode_call_int_op(fwnode, get_reference_args, prop, nargs_prop, > nargs, index, args); > + if (ret == 0) Should this be "if (ret == 0 || IS_ERR_OR_NULL(fwnode->secondary))" ? > + return ret; > > - if (ret < 0 && !IS_ERR_OR_NULL(fwnode) && > - !IS_ERR_OR_NULL(fwnode->secondary)) > - ret = fwnode_call_int_op(fwnode->secondary, get_reference_args, > - prop, nargs_prop, nargs, index, args); > - > - return ret; > + return fwnode_call_int_op(fwnode->secondary, get_reference_args, prop, nargs_prop, > + nargs, index, args); > } > EXPORT_SYMBOL_GPL(fwnode_property_get_reference_args); What happens before this patch is that sfp_bus_find_fwnode() will call fwnode_property_get_reference_args() and the first calls return -ENOENT which sfp_bus_find_fwnode() will handle in a special way. After your patch, -EINVAL is returned, because fwnode_call_int_op() on fwnode->secondary is always called regardless of the return value of the original fwnode. -michael
On Mon, Mar 14, 2022 at 8:51 PM Michael Walle <michael@walle.cc> wrote: > > Hi Andy, > > > Some of the fwnode APIs might return an error pointer instead of NULL > > or valid fwnode handle. The result of such API call may be considered > > optional and hence the test for it is usually done in a form of > > > > fwnode = fwnode_find_reference(...); > > if (IS_ERR(fwnode)) > > ...error handling... > > > > Nevertheless the resulting fwnode may have bumped the reference count > > and hence caller of the above API is obliged to call fwnode_handle_put(). > > Since fwnode may be not valid either as NULL or error pointer the check > > has to be performed there. This approach uglifies the code and adds > > a point of making a mistake, i.e. forgetting about error point case. > > > > To prevent this, allow an error pointer to be passed to the fwnode APIs. > > > > Fixes: 83b34afb6b79 ("device property: Introduce fwnode_find_reference()") > > Reported-by: Nuno Sá <nuno.sa@analog.com> > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > Tested-by: Nuno Sá <nuno.sa@analog.com> > > Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com> > > Acked-by: Nuno Sá <nuno.sa@analog.com> > > This breaks SFP/phylink (using the lan966x switch) on my board. See below > for more details. I'm dropping this commit for the time being. > [..] > > > @@ -480,15 +485,16 @@ int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode, > > { > > int ret; > > > > + if (IS_ERR_OR_NULL(fwnode)) > > + return -ENOENT; > > + > > ret = fwnode_call_int_op(fwnode, get_reference_args, prop, nargs_prop, > > nargs, index, args); > > + if (ret == 0) > > Should this be "if (ret == 0 || IS_ERR_OR_NULL(fwnode->secondary))" ? > > > + return ret; > > > > - if (ret < 0 && !IS_ERR_OR_NULL(fwnode) && > > - !IS_ERR_OR_NULL(fwnode->secondary)) > > - ret = fwnode_call_int_op(fwnode->secondary, get_reference_args, > > - prop, nargs_prop, nargs, index, args); > > - > > - return ret; > > + return fwnode_call_int_op(fwnode->secondary, get_reference_args, prop, nargs_prop, > > + nargs, index, args); > > } > > EXPORT_SYMBOL_GPL(fwnode_property_get_reference_args); > > What happens before this patch is that sfp_bus_find_fwnode() will call > fwnode_property_get_reference_args() and the first calls return -ENOENT > which sfp_bus_find_fwnode() will handle in a special way. After your > patch, -EINVAL is returned, because fwnode_call_int_op() on > fwnode->secondary is always called regardless of the return value of > the original fwnode. > > -michael
On Tue, Mar 15, 2022 at 12:16:01PM +0100, Rafael J. Wysocki wrote: > On Mon, Mar 14, 2022 at 8:51 PM Michael Walle <michael@walle.cc> wrote: ... > > This breaks SFP/phylink (using the lan966x switch) on my board. See below > > for more details. Michael, thank you for the report, I'll investigate it further. > I'm dropping this commit for the time being. Thanks! Fine with me as I think it's not critical (the current or pending users of the fwnode_find_reference() are / will be aware of the error pointer).
On Mon, Mar 14, 2022 at 08:51:37PM +0100, Michael Walle wrote: > This breaks SFP/phylink (using the lan966x switch) on my board. See below > for more details. I have just sent v5 (it's now a series of patches where the first one is the fixed version of this patch), please (re-)test.
diff --git a/drivers/base/property.c b/drivers/base/property.c index c0e94cce9c29..4fbdb14cdec4 100644 --- a/drivers/base/property.c +++ b/drivers/base/property.c @@ -47,12 +47,14 @@ bool fwnode_property_present(const struct fwnode_handle *fwnode, { bool ret; + if (IS_ERR_OR_NULL(fwnode)) + return false; + ret = fwnode_call_bool_op(fwnode, property_present, propname); - if (ret == false && !IS_ERR_OR_NULL(fwnode) && - !IS_ERR_OR_NULL(fwnode->secondary)) - ret = fwnode_call_bool_op(fwnode->secondary, property_present, - propname); - return ret; + if (ret) + return ret; + + return fwnode_call_bool_op(fwnode->secondary, property_present, propname); } EXPORT_SYMBOL_GPL(fwnode_property_present); @@ -232,15 +234,16 @@ static int fwnode_property_read_int_array(const struct fwnode_handle *fwnode, { int ret; + if (IS_ERR_OR_NULL(fwnode)) + return -EINVAL; + ret = fwnode_call_int_op(fwnode, property_read_int_array, propname, elem_size, val, nval); - if (ret == -EINVAL && !IS_ERR_OR_NULL(fwnode) && - !IS_ERR_OR_NULL(fwnode->secondary)) - ret = fwnode_call_int_op( - fwnode->secondary, property_read_int_array, propname, - elem_size, val, nval); + if (ret != -EINVAL) + return ret; - return ret; + return fwnode_call_int_op(fwnode->secondary, property_read_int_array, propname, + elem_size, val, nval); } /** @@ -371,14 +374,16 @@ int fwnode_property_read_string_array(const struct fwnode_handle *fwnode, { int ret; + if (IS_ERR_OR_NULL(fwnode)) + return -EINVAL; + ret = fwnode_call_int_op(fwnode, property_read_string_array, propname, val, nval); - if (ret == -EINVAL && !IS_ERR_OR_NULL(fwnode) && - !IS_ERR_OR_NULL(fwnode->secondary)) - ret = fwnode_call_int_op(fwnode->secondary, - property_read_string_array, propname, - val, nval); - return ret; + if (ret != -EINVAL) + return ret; + + return fwnode_call_int_op(fwnode->secondary, property_read_string_array, propname, + val, nval); } EXPORT_SYMBOL_GPL(fwnode_property_read_string_array); @@ -480,15 +485,16 @@ int fwnode_property_get_reference_args(const struct fwnode_handle *fwnode, { int ret; + if (IS_ERR_OR_NULL(fwnode)) + return -ENOENT; + ret = fwnode_call_int_op(fwnode, get_reference_args, prop, nargs_prop, nargs, index, args); + if (ret == 0) + return ret; - if (ret < 0 && !IS_ERR_OR_NULL(fwnode) && - !IS_ERR_OR_NULL(fwnode->secondary)) - ret = fwnode_call_int_op(fwnode->secondary, get_reference_args, - prop, nargs_prop, nargs, index, args); - - return ret; + return fwnode_call_int_op(fwnode->secondary, get_reference_args, prop, nargs_prop, + nargs, index, args); } EXPORT_SYMBOL_GPL(fwnode_property_get_reference_args); @@ -698,7 +704,7 @@ fwnode_get_next_available_child_node(const struct fwnode_handle *fwnode, { struct fwnode_handle *next_child = child; - if (!fwnode) + if (IS_ERR_OR_NULL(fwnode)) return NULL; do { @@ -722,16 +728,16 @@ struct fwnode_handle *device_get_next_child_node(struct device *dev, const struct fwnode_handle *fwnode = dev_fwnode(dev); struct fwnode_handle *next; + if (IS_ERR_OR_NULL(fwnode)) + return NULL; + /* Try to find a child in primary fwnode */ next = fwnode_get_next_child_node(fwnode, child); if (next) return next; /* When no more children in primary, continue with secondary */ - if (fwnode && !IS_ERR_OR_NULL(fwnode->secondary)) - next = fwnode_get_next_child_node(fwnode->secondary, child); - - return next; + return fwnode_get_next_child_node(fwnode->secondary, child); } EXPORT_SYMBOL_GPL(device_get_next_child_node); @@ -798,6 +804,9 @@ EXPORT_SYMBOL_GPL(fwnode_handle_put); */ bool fwnode_device_is_available(const struct fwnode_handle *fwnode) { + if (IS_ERR_OR_NULL(fwnode)) + return false; + if (!fwnode_has_op(fwnode, device_is_available)) return true; @@ -988,14 +997,14 @@ fwnode_graph_get_next_endpoint(const struct fwnode_handle *fwnode, parent = fwnode_graph_get_port_parent(prev); else parent = fwnode; + if (IS_ERR_OR_NULL(parent)) + return NULL; ep = fwnode_call_ptr_op(parent, graph_get_next_endpoint, prev); + if (ep) + return ep; - if (IS_ERR_OR_NULL(ep) && - !IS_ERR_OR_NULL(parent) && !IS_ERR_OR_NULL(parent->secondary)) - ep = fwnode_graph_get_next_endpoint(parent->secondary, NULL); - - return ep; + return fwnode_graph_get_next_endpoint(parent->secondary, NULL); } EXPORT_SYMBOL_GPL(fwnode_graph_get_next_endpoint); diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h index 3a532ba66f6c..7defac04f9a3 100644 --- a/include/linux/fwnode.h +++ b/include/linux/fwnode.h @@ -148,12 +148,12 @@ struct fwnode_operations { int (*add_links)(struct fwnode_handle *fwnode); }; -#define fwnode_has_op(fwnode, op) \ - ((fwnode) && (fwnode)->ops && (fwnode)->ops->op) +#define fwnode_has_op(fwnode, op) \ + (!IS_ERR_OR_NULL(fwnode) && (fwnode)->ops && (fwnode)->ops->op) + #define fwnode_call_int_op(fwnode, op, ...) \ - (fwnode ? (fwnode_has_op(fwnode, op) ? \ - (fwnode)->ops->op(fwnode, ## __VA_ARGS__) : -ENXIO) : \ - -EINVAL) + (fwnode_has_op(fwnode, op) ? \ + (fwnode)->ops->op(fwnode, ## __VA_ARGS__) : (IS_ERR_OR_NULL(fwnode) ? -EINVAL : -ENXIO)) #define fwnode_call_bool_op(fwnode, op, ...) \ (fwnode_has_op(fwnode, op) ? \
Some of the fwnode APIs might return an error pointer instead of NULL or valid fwnode handle. The result of such API call may be considered optional and hence the test for it is usually done in a form of fwnode = fwnode_find_reference(...); if (IS_ERR(fwnode)) ...error handling... Nevertheless the resulting fwnode may have bumped the reference count and hence caller of the above API is obliged to call fwnode_handle_put(). Since fwnode may be not valid either as NULL or error pointer the check has to be performed there. This approach uglifies the code and adds a point of making a mistake, i.e. forgetting about error point case. To prevent this, allow an error pointer to be passed to the fwnode APIs. Fixes: 83b34afb6b79 ("device property: Introduce fwnode_find_reference()") Reported-by: Nuno Sá <nuno.sa@analog.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Tested-by: Nuno Sá <nuno.sa@analog.com> Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com> Acked-by: Nuno Sá <nuno.sa@analog.com> --- v4: dropped unneeded fwnode.h and ' == true' part (Sakari), added tag (Sakari) drivers/base/property.c | 75 +++++++++++++++++++++++------------------ include/linux/fwnode.h | 10 +++--- 2 files changed, 47 insertions(+), 38 deletions(-)