On 12/28/21 8:28 PM, Jiasheng Jiang wrote:
On Tue, Dec 28, 2021 at 10:50:22PM +0800, Alex Elder wrote:
But the two places you're returning are in the middle of a loop (in gbaudio_tplg_create_widget() and gbaudio_tplg_process_kcontrols()). Each is building up a sort of hierarchical data structure, and as you can see, the existing code takes care to de-construct the partially built structure in the event an error occurs before it completes.
There is a chance that your simple return would "work", but by reading the surrounding code you should recognize that the proper way to handle the error is to jump to the cleanup at the end.
Yes, I agree with your opinion and this time I use "goto error" instead of directly return in the two callers. The new patch is as follow.
As the possible alloc failure of devm_kcalloc(), it could return null pointer. Therefore, 'strings' should be checked and return NULL if alloc fails to prevent the dereference of the NULL pointer. Also, the caller should also deal with the return value of the gb_generate_enum_strings() and return -ENOMEM if returns NULL. Moreover, because the memory allocated with devm_kzalloc() will be freed automatically when the last reference to the device is dropped, the 'gbe' in gbaudio_tplg_create_enum_kctl() and gbaudio_tplg_create_enum_ctl() do not need to free manually. But the 'control' in gbaudio_tplg_create_widget() and gbaudio_tplg_process_kcontrols() has a specially error handle to cleanup. So it should be better to cleanup 'control' when fails.
I haven't really looked at this yet, but in any case I would like you to send version 3 of this patch.
The reason is that you should not include the message above in the patch itself.
To be clear, I really appreciate your response; please *do* respond to review comments. But do so in e-mail only, and then follow up with a new patch, using the same basic subject (with a new version) and (roughly) the same description.
So your patch should have a subject line with v3. It should then contain the original description (not indented with ">>" or anything), updated or improved if appropriate to reflect the current state of the patch. Then, below the "---" line you should include a patch history, with a line or two describing each version. For example, it might look something like:
--- v3: Same code as v2, but fixed description as requested. v2: Updated to use common error processing at the end of both gbaudio_tplg_create_widget() and gbaudio_tplg_process_kcontrols().
I will review version 3, and if I don't see anything else wrong with it I'll offer a "Signed-off-by" tag.
-Alex
Fixes: e65579e335da ("greybus: audio: topology: Enable enumerated control support") Signed-off-by: Jiasheng Jiang jiasheng@iscas.ac.cn
Changelog:
v1 -> v2
*Change 1. Add the cleanup process when alloc fails in two callers and refine the commit message.
drivers/staging/greybus/audio_topology.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/drivers/staging/greybus/audio_topology.c b/drivers/staging/greybus/audio_topology.c index 1fc7727ab7be..6bba735d2e5c 100644 --- a/drivers/staging/greybus/audio_topology.c +++ b/drivers/staging/greybus/audio_topology.c @@ -147,6 +147,9 @@ static const char **gb_generate_enum_strings(struct gbaudio_module_info *gb, items = le32_to_cpu(gbenum->items); strings = devm_kcalloc(gb->dev, items, sizeof(char *), GFP_KERNEL);
- if (!strings)
return NULL;- data = gbenum->names;
for (i = 0; i < items; i++) { @@ -655,6 +658,8 @@ static int gbaudio_tplg_create_enum_kctl(struct gbaudio_module_info *gb, /* since count=1, and reg is dummy */ gbe->items = le32_to_cpu(gb_enum->items); gbe->texts = gb_generate_enum_strings(gb, gb_enum);
- if (!gbe->texts)
return -ENOMEM;/* debug enum info */ dev_dbg(gb->dev, "Max:%d, name_length:%d\n", gbe->items, @@ -862,6 +867,8 @@ static int gbaudio_tplg_create_enum_ctl(struct gbaudio_module_info *gb, /* since count=1, and reg is dummy */ gbe->items = le32_to_cpu(gb_enum->items); gbe->texts = gb_generate_enum_strings(gb, gb_enum);
- if (!gbe->texts)
return -ENOMEM;/* debug enum info */ dev_dbg(gb->dev, "Max:%d, name_length:%d\n", gbe->items, @@ -1034,6 +1041,10 @@ static int gbaudio_tplg_create_widget(struct gbaudio_module_info *module, csize += le16_to_cpu(gbenum->names_length); control->texts = (const char * const *) gb_generate_enum_strings(module, gbenum);
if (!control->texts) {ret = -ENOMEM;goto error;} control->items = le32_to_cpu(gbenum->items);@@ -1183,6 +1194,10 @@ static int gbaudio_tplg_process_kcontrols(struct gbaudio_module_info *module, csize += le16_to_cpu(gbenum->names_length); control->texts = (const char * const *) gb_generate_enum_strings(module, gbenum);
if (!control->texts) {ret = -ENOMEM;goto error;} control->items = le32_to_cpu(gbenum->items);