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SubjectRe:Re: [PATCH] firmware: arm_scpi: Fix error handle when scpi probe failed

>On Fri, Jul 01, 2022 at 06:04:53PM +0800, huhai wrote:
>>
>> scpi_info is a global variable, we must set it to NULL when it is not valid
>
>How about not assigning the global variable until the end of the probe ?

>Something like below:>
>Regards,
>Sudeep
>
>-->8
>
>diff --git i/drivers/firmware/arm_scpi.c w/drivers/firmware/arm_scpi.c
>index ddf0b9ff9e15..5463501735ff 100644
>--- i/drivers/firmware/arm_scpi.c
>+++ w/drivers/firmware/arm_scpi.c
>@@ -913,13 +913,14 @@ static int scpi_probe(struct platform_device *pdev)
> struct resource res;
> struct device *dev = &pdev->dev;
> struct device_node *np = dev->of_node;
>+ struct scpi_drvinfo *scpi_drvinfo;
>
>- scpi_info = devm_kzalloc(dev, sizeof(*scpi_info), GFP_KERNEL);
>- if (!scpi_info)
>+ scpi_drvinfo = devm_kzalloc(dev, sizeof(*scpi_drvinfo), GFP_KERNEL);
>+ if (!scpi_drvinfo)
> return -ENOMEM;
>
> if (of_match_device(legacy_scpi_of_match, &pdev->dev))
>- scpi_info->is_legacy = true;
>+ scpi_drvinfo->is_legacy = true;
>
> count = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
> if (count < 0) {
>@@ -927,19 +928,19 @@ static int scpi_probe(struct platform_device *pdev)
> return -ENODEV;
> }
>
>- scpi_info->channels = devm_kcalloc(dev, count, sizeof(struct scpi_chan),
>- GFP_KERNEL);
>- if (!scpi_info->channels)
>+ scpi_drvinfo->channels =
>+ devm_kcalloc(dev, count, sizeof(struct scpi_chan), GFP_KERNEL);
>+ if (!scpi_drvinfo->channels)
> return -ENOMEM;
>
>- ret = devm_add_action(dev, scpi_free_channels, scpi_info);
>+ ret = devm_add_action(dev, scpi_free_channels, scpi_drvinfo);
> if (ret)
> return ret;
>
>- for (; scpi_info->num_chans < count; scpi_info->num_chans++) {
>+ for (; scpi_drvinfo->num_chans < count; scpi_drvinfo->num_chans++) {
> resource_size_t size;
>- int idx = scpi_info->num_chans;
>- struct scpi_chan *pchan = scpi_info->channels + idx;
>+ int idx = scpi_drvinfo->num_chans;
>+ struct scpi_chan *pchan = scpi_drvinfo->channels + idx;
> struct mbox_client *cl = &pchan->cl;
> struct device_node *shmem = of_parse_phandle(np, "shmem", idx);
>
>@@ -986,43 +987,44 @@ static int scpi_probe(struct platform_device *pdev)
> return ret;
> }
>
>- scpi_info->commands = scpi_std_commands;
>+ scpi_drvinfo->commands = scpi_std_commands;
>
>- platform_set_drvdata(pdev, scpi_info);
>+ platform_set_drvdata(pdev, scpi_drvinfo);
>
>- if (scpi_info->is_legacy) {
>+ if (scpi_drvinfo->is_legacy) {
> /* Replace with legacy variants */
> scpi_ops.clk_set_val = legacy_scpi_clk_set_val;
>- scpi_info->commands = scpi_legacy_commands;
>+ scpi_drvinfo->commands = scpi_legacy_commands;
>
> /* Fill priority bitmap */
> for (idx = 0; idx < ARRAY_SIZE(legacy_hpriority_cmds); idx++)
> set_bit(legacy_hpriority_cmds[idx],
>- scpi_info->cmd_priority);
>+ scpi_drvinfo->cmd_priority);
> }
>
>- ret = scpi_init_versions(scpi_info);
>+ ret = scpi_init_versions(scpi_drvinfo);
> if (ret) {
> dev_err(dev, "incorrect or no SCP firmware found\n");
> return ret;
> }
>
>- if (scpi_info->is_legacy && !scpi_info->protocol_version &&
>- !scpi_info->firmware_version)
>+ if (scpi_drvinfo->is_legacy && !scpi_drvinfo->protocol_version &&
>+ !scpi_drvinfo->firmware_version)
> dev_info(dev, "SCP Protocol legacy pre-1.0 firmware\n");
> else
> dev_info(dev, "SCP Protocol %lu.%lu Firmware %lu.%lu.%lu version\n",
> FIELD_GET(PROTO_REV_MAJOR_MASK,
>- scpi_info->protocol_version),
>+ scpi_drvinfo->protocol_version),
> FIELD_GET(PROTO_REV_MINOR_MASK,
>- scpi_info->protocol_version),
>+ scpi_drvinfo->protocol_version),
> FIELD_GET(FW_REV_MAJOR_MASK,
>- scpi_info->firmware_version),
>+ scpi_drvinfo->firmware_version),
> FIELD_GET(FW_REV_MINOR_MASK,
>- scpi_info->firmware_version),
>+ scpi_drvinfo->firmware_version),
> FIELD_GET(FW_REV_PATCH_MASK,
>- scpi_info->firmware_version));
>- scpi_info->scpi_ops = &scpi_ops;
>+ scpi_drvinfo->firmware_version));
>+ scpi_drvinfo->scpi_ops = &scpi_ops;

>+ scpi_info = scpi_drvinfo;

Yes, I think this patch will work well until it runs here.

>

> return devm_of_platform_populate(dev);

we should not return devm_of_platform_populate() directly, because devm_of_platform_populate()
may fails, if it fails, the scpi_info will pointing to free-ed memory.

as you said before:
- return devm_of_platform_populate(dev);
+ devm_of_platform_populate(dev);
+
+ return ret;
will work well.

thanks

> }
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