Hi, On 9/26/23 20:42, Fernando Eckhardt Valle (FIPT) wrote: > Thanks for the review Hans, I'll send a new version with some adjustments. > >> Note this is just a preference you keen keep this as is >> if you want, > I liked the Ilpo suggestion, with two 'gotos' is eliminated repeated code. If everything is ok, I prefer it this way. If you prefer the 2 goto solution from v5 then keeping it as is is fine. Regards, Hans > ________________________________________ > From: Hans de Goede <hdegoede@xxxxxxxxxx> > Sent: Tuesday, September 26, 2023 7:23 AM > To: Fernando Eckhardt Valle (FIPT); ilpo.jarvinen@xxxxxxxxxxxxxxx; mpearson-lenovo@xxxxxxxxx; corbet@xxxxxxx; hmh@xxxxxxxxxx; markgross@xxxxxxxxxx; linux-doc@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; ibm-acpi-devel@xxxxxxxxxxxxxxxxxxxxx; platform-driver-x86@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v5] platform/x86: thinkpad_acpi: sysfs interface to auxmac > > Hi, > > It looks like I just reviewed an old version, reviewing this version now ... > > On 9/25/23 20:41, Fernando Eckhardt Valle wrote: >> Newer Thinkpads have a feature called MAC Address Pass-through. >> This patch provides a sysfs interface that userspace can use >> to get this auxiliary mac address. >> >> Signed-off-by: Fernando Eckhardt Valle <fevalle@xxxxxx> >> --- >> Changes in v5: >> - Repeated code deleted. >> - Adjusted offset of a strscpy(). >> Changes in v4: >> - strscpy() in all string copies. >> Changes in v3: >> - Added null terminator to auxmac string when copying auxiliary >> mac address value. >> Changes in v2: >> - Added documentation. >> - All handling of the auxmac value is done in the _init function. >> --- >> .../admin-guide/laptops/thinkpad-acpi.rst | 20 +++++ >> drivers/platform/x86/thinkpad_acpi.c | 81 +++++++++++++++++++ >> 2 files changed, 101 insertions(+) >> >> diff --git a/Documentation/admin-guide/laptops/thinkpad-acpi.rst b/Documentation/admin-guide/laptops/thinkpad-acpi.rst >> index e27a1c3f6..98d304010 100644 >> --- a/Documentation/admin-guide/laptops/thinkpad-acpi.rst >> +++ b/Documentation/admin-guide/laptops/thinkpad-acpi.rst >> @@ -53,6 +53,7 @@ detailed description): >> - Lap mode sensor >> - Setting keyboard language >> - WWAN Antenna type >> + - Auxmac >> >> A compatibility table by model and feature is maintained on the web >> site, http://ibm-acpi.sf.net/. I appreciate any success or failure >> @@ -1511,6 +1512,25 @@ Currently 2 antenna types are supported as mentioned below: >> The property is read-only. If the platform doesn't have support the sysfs >> class is not created. >> >> +Auxmac >> +------ >> + >> +sysfs: auxmac >> + >> +Some newer Thinkpads have a feature called MAC Address Pass-through. This >> +feature is implemented by the system firmware to provide a system unique MAC, >> +that can override a dock or USB ethernet dongle MAC, when connected to a >> +network. This property enables user-space to easily determine the MAC address >> +if the feature is enabled. >> + >> +The values of this auxiliary MAC are: >> + >> + cat /sys/devices/platform/thinkpad_acpi/auxmac >> + >> +If the feature is disabled, the value will be 'disabled'. >> + >> +This property is read-only. >> + >> Adaptive keyboard >> ----------------- >> >> diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c >> index d70c89d32..2324ebb46 100644 >> --- a/drivers/platform/x86/thinkpad_acpi.c >> +++ b/drivers/platform/x86/thinkpad_acpi.c >> @@ -10785,6 +10785,82 @@ static struct ibm_struct dprc_driver_data = { >> .name = "dprc", >> }; >> >> +/* >> + * Auxmac >> + * >> + * This auxiliary mac address is enabled in the bios through the >> + * MAC Address Pass-through feature. In most cases, there are three >> + * possibilities: Internal Mac, Second Mac, and disabled. >> + * >> + */ >> + >> +#define AUXMAC_LEN 12 >> +#define AUXMAC_START 9 >> +#define AUXMAC_STRLEN 22 >> +#define AUXMAC_BEGIN_MARKER 8 >> +#define AUXMAC_END_MARKER 21 >> + >> +static char auxmac[AUXMAC_LEN + 1]; >> + >> +static int auxmac_init(struct ibm_init_struct *iibm) >> +{ >> + acpi_status status; >> + struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL }; >> + union acpi_object *obj; >> + >> + status = acpi_evaluate_object(NULL, "\\MACA", NULL, &buffer); >> + >> + if (ACPI_FAILURE(status)) >> + return -ENODEV; > > In this code path you don't initialize the "auxmac" buffer at all, > but your auxmac_attr_group does not have an is_visible callback, > so the auxmax sysfs attr will still show up. > > Please add an is_visible callback and retuern 0 (not visible) > when auxmac[0] == 0; See existing is_visible code for some > examples. > >> + >> + obj = buffer.pointer; >> + >> + if (obj->type != ACPI_TYPE_STRING || obj->string.length != AUXMAC_STRLEN) { >> + pr_info("Invalid buffer for MAC address pass-through.\n"); >> + goto auxmacinvalid; >> + } >> + >> + if (obj->string.pointer[AUXMAC_BEGIN_MARKER] != '#' || >> + obj->string.pointer[AUXMAC_END_MARKER] != '#') { >> + pr_info("Invalid header for MAC address pass-through.\n"); >> + goto auxmacinvalid; >> + } >> + >> + if (strncmp(obj->string.pointer + AUXMAC_START, "XXXXXXXXXXXX", AUXMAC_LEN) != 0) >> + strscpy(auxmac, obj->string.pointer + AUXMAC_START, AUXMAC_LEN + 1); > > Please use sizeof(auxmac) as last parameter to strscpy() here. > >> + else >> + strscpy(auxmac, "disabled", AUXMAC_LEN); > > Please use sizeof(auxmac) as last parameter to strscpy() here. > > Also note how you pass 2 different dest-sizes for the same dest buffer before, > which looks weird ... > > >> + >> +free: >> + kfree(obj); >> + return 0; >> + >> +auxmacinvalid: >> + strscpy(auxmac, "unavailable", AUXMAC_LEN); >> + goto free; >> +} > > I'm not liking the goto dance here, I would prefer: > > kfree(obj); > return 0; > > auxmacinvalid: > strscpy(auxmac, "unavailable", AUXMAC_LEN); > kfree(obj); > return 0; > > It is quite normal for an error-exit path to repeat a kfree(). > > Note this is just a preference you keen keep this as is > if you want, but to me the goto free which jumps up looks > pretty weird. > > Regards, > > Hans > > > >> + >> +static struct ibm_struct auxmac_data = { >> + .name = "auxmac", >> +}; >> + >> +static ssize_t auxmac_show(struct device *dev, >> + struct device_attribute *attr, >> + char *buf) >> +{ >> + return sysfs_emit(buf, "%s\n", auxmac); >> +} >> +static DEVICE_ATTR_RO(auxmac); >> + >> +static struct attribute *auxmac_attributes[] = { >> + &dev_attr_auxmac.attr, >> + NULL >> +}; >> + >> +static const struct attribute_group auxmac_attr_group = { >> + .attrs = auxmac_attributes, >> +}; >> + >> /* --------------------------------------------------------------------- */ >> >> static struct attribute *tpacpi_driver_attributes[] = { >> @@ -10843,6 +10919,7 @@ static const struct attribute_group *tpacpi_groups[] = { >> &proxsensor_attr_group, >> &kbdlang_attr_group, >> &dprc_attr_group, >> + &auxmac_attr_group, >> NULL, >> }; >> >> @@ -11414,6 +11491,10 @@ static struct ibm_init_struct ibms_init[] __initdata = { >> .init = tpacpi_dprc_init, >> .data = &dprc_driver_data, >> }, >> + { >> + .init = auxmac_init, >> + .data = &auxmac_data, >> + }, >> }; >> >> static int __init set_ibm_param(const char *val, const struct kernel_param *kp) > >
