ath10k_dbg() is called in ath10k_process_rx() with huge set of arguments
which is causing CPU overhead even when debug_mask is not set.
Good improvement was observed in the receive side performance when call
to ath10k_dbg() is avoided in the RX path.
Since currently all debug messages are sent via tracing infrastructure,
we cannot entirely avoid calling ath10k_dbg. Therefore, call to
ath10k_dbg() is made conditional based on tracing config in the driver.
Trasmit performance remains unchanged with this patch; below are some
experimental results with this patch and tracing disabled.
mesh mode:
w/o this patch with this patch
Traffic TP CPU Usage TP CPU usage
TCP 840Mbps 76.53% 960Mbps 78.14%
UDP 1030Mbps 74.58% 1132Mbps 74.31%
Infra mode:
w/o this patch with this patch
Traffic TP CPU Usage TP CPU usage
TCP Rx 1241Mbps 80.89% 1270Mbps 73.50%
UDP Rx 1433Mbps 81.77% 1472Mbps 72.80%
Tested platform : IPQ8064
hardware used : QCA9984
firmware ver : ver 10.4-3.5.3-00057
Signed-off-by: Kan Yan <[email protected]>
Signed-off-by: Venkateswara Naralasetty <[email protected]>
---
v2:
* changed trace enabled check from IS_ENABLED(CONFIG_ATH10K_TRACING)
* to trace_ath10k_log_dbg_enabled().
drivers/net/wireless/ath/ath10k/core.c | 2 ++
drivers/net/wireless/ath/ath10k/debug.c | 8 ++++----
drivers/net/wireless/ath/ath10k/debug.h | 22 ++++++++++++++++------
drivers/net/wireless/ath/ath10k/trace.c | 1 +
drivers/net/wireless/ath/ath10k/trace.h | 6 +++++-
5 files changed, 28 insertions(+), 11 deletions(-)
diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
index cfd7bb2..ab709bf 100644
--- a/drivers/net/wireless/ath/ath10k/core.c
+++ b/drivers/net/wireless/ath/ath10k/core.c
@@ -26,6 +26,8 @@
#include "coredump.h"
unsigned int ath10k_debug_mask;
+EXPORT_SYMBOL(ath10k_debug_mask);
+
static unsigned int ath10k_cryptmode_param;
static bool uart_print;
static bool skip_otp;
diff --git a/drivers/net/wireless/ath/ath10k/debug.c b/drivers/net/wireless/ath/ath10k/debug.c
index 32d967a..1b63929 100644
--- a/drivers/net/wireless/ath/ath10k/debug.c
+++ b/drivers/net/wireless/ath/ath10k/debug.c
@@ -2620,8 +2620,8 @@ void ath10k_debug_unregister(struct ath10k *ar)
#endif /* CONFIG_ATH10K_DEBUGFS */
#ifdef CONFIG_ATH10K_DEBUG
-void ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
- const char *fmt, ...)
+void __ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
+ const char *fmt, ...)
{
struct va_format vaf;
va_list args;
@@ -2638,7 +2638,7 @@ void ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
va_end(args);
}
-EXPORT_SYMBOL(ath10k_dbg);
+EXPORT_SYMBOL(__ath10k_dbg);
void ath10k_dbg_dump(struct ath10k *ar,
enum ath10k_debug_mask mask,
@@ -2651,7 +2651,7 @@ void ath10k_dbg_dump(struct ath10k *ar,
if (ath10k_debug_mask & mask) {
if (msg)
- ath10k_dbg(ar, mask, "%s\n", msg);
+ __ath10k_dbg(ar, mask, "%s\n", msg);
for (ptr = buf; (ptr - buf) < len; ptr += 16) {
linebuflen = 0;
diff --git a/drivers/net/wireless/ath/ath10k/debug.h b/drivers/net/wireless/ath/ath10k/debug.h
index db78e85..a5b2039 100644
--- a/drivers/net/wireless/ath/ath10k/debug.h
+++ b/drivers/net/wireless/ath/ath10k/debug.h
@@ -240,18 +240,18 @@ void ath10k_sta_update_rx_tid_stats_ampdu(struct ath10k *ar,
#endif /* CONFIG_MAC80211_DEBUGFS */
#ifdef CONFIG_ATH10K_DEBUG
-__printf(3, 4) void ath10k_dbg(struct ath10k *ar,
- enum ath10k_debug_mask mask,
- const char *fmt, ...);
+__printf(3, 4) void __ath10k_dbg(struct ath10k *ar,
+ enum ath10k_debug_mask mask,
+ const char *fmt, ...);
void ath10k_dbg_dump(struct ath10k *ar,
enum ath10k_debug_mask mask,
const char *msg, const char *prefix,
const void *buf, size_t len);
#else /* CONFIG_ATH10K_DEBUG */
-static inline int ath10k_dbg(struct ath10k *ar,
- enum ath10k_debug_mask dbg_mask,
- const char *fmt, ...)
+static inline int __ath10k_dbg(struct ath10k *ar,
+ enum ath10k_debug_mask dbg_mask,
+ const char *fmt, ...)
{
return 0;
}
@@ -263,4 +263,14 @@ static inline void ath10k_dbg_dump(struct ath10k *ar,
{
}
#endif /* CONFIG_ATH10K_DEBUG */
+
+/* Avoid calling __ath10k_dbg() if debug_mask is not set and tracing
+ * disabled.
+ */
+#define ath10k_dbg(ar, dbg_mask, fmt, ...) \
+do { \
+ if ((ath10k_debug_mask & dbg_mask) || \
+ trace_ath10k_log_dbg_enabled()) \
+ __ath10k_dbg(ar, dbg_mask, fmt, ##__VA_ARGS__); \
+} while (0)
#endif /* _DEBUG_H_ */
diff --git a/drivers/net/wireless/ath/ath10k/trace.c b/drivers/net/wireless/ath/ath10k/trace.c
index 3ecdff1..c7d4c97 100644
--- a/drivers/net/wireless/ath/ath10k/trace.c
+++ b/drivers/net/wireless/ath/ath10k/trace.c
@@ -7,3 +7,4 @@
#define CREATE_TRACE_POINTS
#include "trace.h"
+EXPORT_SYMBOL(__tracepoint_ath10k_log_dbg);
diff --git a/drivers/net/wireless/ath/ath10k/trace.h b/drivers/net/wireless/ath/ath10k/trace.h
index ba977bb..ab91645 100644
--- a/drivers/net/wireless/ath/ath10k/trace.h
+++ b/drivers/net/wireless/ath/ath10k/trace.h
@@ -29,7 +29,11 @@ static inline u32 ath10k_frm_hdr_len(const void *buf, size_t len)
#if !defined(CONFIG_ATH10K_TRACING)
#undef TRACE_EVENT
#define TRACE_EVENT(name, proto, ...) \
-static inline void trace_ ## name(proto) {}
+static inline void trace_ ## name(proto) {} \
+static inline bool trace_##name##_enabled(void) \
+{ \
+ return false; \
+}
#undef DECLARE_EVENT_CLASS
#define DECLARE_EVENT_CLASS(...)
#undef DEFINE_EVENT
--
2.7.4
On 4/26/19 5:58 AM, Venkateswara Naralasetty wrote:
> ath10k_dbg() is called in ath10k_process_rx() with huge set of arguments
> which is causing CPU overhead even when debug_mask is not set.
> Good improvement was observed in the receive side performance when call
> to ath10k_dbg() is avoided in the RX path.
>
> Since currently all debug messages are sent via tracing infrastructure,
> we cannot entirely avoid calling ath10k_dbg. Therefore, call to
> ath10k_dbg() is made conditional based on tracing config in the driver.
>
> Trasmit performance remains unchanged with this patch; below are some
> experimental results with this patch and tracing disabled.
>
> mesh mode:
>
> w/o this patch with this patch
> Traffic TP CPU Usage TP CPU usage
>
> TCP 840Mbps 76.53% 960Mbps 78.14%
> UDP 1030Mbps 74.58% 1132Mbps 74.31%
>
> Infra mode:
>
> w/o this patch with this patch
> Traffic TP CPU Usage TP CPU usage
>
> TCP Rx 1241Mbps 80.89% 1270Mbps 73.50%
> UDP Rx 1433Mbps 81.77% 1472Mbps 72.80%
>
> Tested platform : IPQ8064
> hardware used : QCA9984
> firmware ver : ver 10.4-3.5.3-00057
>
> Signed-off-by: Kan Yan <[email protected]>
> Signed-off-by: Venkateswara Naralasetty <[email protected]>
> ---
> v2:
> * changed trace enabled check from IS_ENABLED(CONFIG_ATH10K_TRACING)
> * to trace_ath10k_log_dbg_enabled().
>
> drivers/net/wireless/ath/ath10k/core.c | 2 ++
> drivers/net/wireless/ath/ath10k/debug.c | 8 ++++----
> drivers/net/wireless/ath/ath10k/debug.h | 22 ++++++++++++++++------
> drivers/net/wireless/ath/ath10k/trace.c | 1 +
> drivers/net/wireless/ath/ath10k/trace.h | 6 +++++-
> 5 files changed, 28 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath10k/core.c b/drivers/net/wireless/ath/ath10k/core.c
> index cfd7bb2..ab709bf 100644
> --- a/drivers/net/wireless/ath/ath10k/core.c
> +++ b/drivers/net/wireless/ath/ath10k/core.c
> @@ -26,6 +26,8 @@
> #include "coredump.h"
>
> unsigned int ath10k_debug_mask;
> +EXPORT_SYMBOL(ath10k_debug_mask);
> +
> static unsigned int ath10k_cryptmode_param;
> static bool uart_print;
> static bool skip_otp;
> diff --git a/drivers/net/wireless/ath/ath10k/debug.c b/drivers/net/wireless/ath/ath10k/debug.c
> index 32d967a..1b63929 100644
> --- a/drivers/net/wireless/ath/ath10k/debug.c
> +++ b/drivers/net/wireless/ath/ath10k/debug.c
> @@ -2620,8 +2620,8 @@ void ath10k_debug_unregister(struct ath10k *ar)
> #endif /* CONFIG_ATH10K_DEBUGFS */
>
> #ifdef CONFIG_ATH10K_DEBUG
> -void ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
> - const char *fmt, ...)
> +void __ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
> + const char *fmt, ...)
> {
> struct va_format vaf;
> va_list args;
Do you still need the check later in this method:
if (ath10k_debug_mask & mask)
since you already checked in the ath10k_dbg() macro?
Thanks,
Ben
--
Ben Greear <[email protected]>
Candela Technologies Inc http://www.candelatech.com
> -----Original Message-----
> From: ath10k <[email protected]> On Behalf Of Ben
> Greear
> Sent: Friday, April 26, 2019 6:52 PM
> To: Venkateswara Naralasetty <[email protected]>;
> [email protected]
> Cc: Kan Yan <[email protected]>; [email protected]
> Subject: [EXT] Re: [PATCHv2] ath10k: Add wrapper function to ath10k debug
>
> On 4/26/19 5:58 AM, Venkateswara Naralasetty wrote:
> > ath10k_dbg() is called in ath10k_process_rx() with huge set of
> > arguments which is causing CPU overhead even when debug_mask is not
> set.
> > Good improvement was observed in the receive side performance when
> > call to ath10k_dbg() is avoided in the RX path.
> >
> > Since currently all debug messages are sent via tracing
> > infrastructure, we cannot entirely avoid calling ath10k_dbg.
> > Therefore, call to
> > ath10k_dbg() is made conditional based on tracing config in the driver.
> >
> > Trasmit performance remains unchanged with this patch; below are some
> > experimental results with this patch and tracing disabled.
> >
> > mesh mode:
> >
> > w/o this patch with this patch
> > Traffic TP CPU Usage TP CPU usage
> >
> > TCP 840Mbps 76.53% 960Mbps 78.14%
> > UDP 1030Mbps 74.58% 1132Mbps 74.31%
> >
> > Infra mode:
> >
> > w/o this patch with this patch
> > Traffic TP CPU Usage TP CPU usage
> >
> > TCP Rx 1241Mbps 80.89% 1270Mbps 73.50%
> > UDP Rx 1433Mbps 81.77% 1472Mbps 72.80%
> >
> > Tested platform : IPQ8064
> > hardware used : QCA9984
> > firmware ver : ver 10.4-3.5.3-00057
> >
> > Signed-off-by: Kan Yan <[email protected]>
> > Signed-off-by: Venkateswara Naralasetty <[email protected]>
> > ---
> > v2:
> > * changed trace enabled check from
> IS_ENABLED(CONFIG_ATH10K_TRACING)
> > * to trace_ath10k_log_dbg_enabled().
> >
> > drivers/net/wireless/ath/ath10k/core.c | 2 ++
> > drivers/net/wireless/ath/ath10k/debug.c | 8 ++++----
> > drivers/net/wireless/ath/ath10k/debug.h | 22 ++++++++++++++++------
> > drivers/net/wireless/ath/ath10k/trace.c | 1 +
> > drivers/net/wireless/ath/ath10k/trace.h | 6 +++++-
> > 5 files changed, 28 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/net/wireless/ath/ath10k/core.c
> > b/drivers/net/wireless/ath/ath10k/core.c
> > index cfd7bb2..ab709bf 100644
> > --- a/drivers/net/wireless/ath/ath10k/core.c
> > +++ b/drivers/net/wireless/ath/ath10k/core.c
> > @@ -26,6 +26,8 @@
> > #include "coredump.h"
> >
> > unsigned int ath10k_debug_mask;
> > +EXPORT_SYMBOL(ath10k_debug_mask);
> > +
> > static unsigned int ath10k_cryptmode_param;
> > static bool uart_print;
> > static bool skip_otp;
> > diff --git a/drivers/net/wireless/ath/ath10k/debug.c
> > b/drivers/net/wireless/ath/ath10k/debug.c
> > index 32d967a..1b63929 100644
> > --- a/drivers/net/wireless/ath/ath10k/debug.c
> > +++ b/drivers/net/wireless/ath/ath10k/debug.c
> > @@ -2620,8 +2620,8 @@ void ath10k_debug_unregister(struct ath10k *ar)
> > #endif /* CONFIG_ATH10K_DEBUGFS */
> >
> > #ifdef CONFIG_ATH10K_DEBUG
> > -void ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
> > - const char *fmt, ...)
> > +void __ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
> > + const char *fmt, ...)
> > {
> > struct va_format vaf;
> > va_list args;
>
> Do you still need the check later in this method:
>
> if (ath10k_debug_mask & mask)
>
> since you already checked in the ath10k_dbg() macro?
Yes, we need this check.
Otherwise all debug messages will be printed even without any debug mask set in case of tracing enabled.
>
> Thanks,
> Ben
>
>
> --
> Ben Greear <[email protected]>
> Candela Technologies Inc http://www.candelatech.com
>
>
> _______________________________________________
> ath10k mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/ath10k
On Fri, 26 Apr 2019 at 14:58, Venkateswara Naralasetty
<[email protected]> wrote:
>
> ath10k_dbg() is called in ath10k_process_rx() with huge set of arguments
> which is causing CPU overhead even when debug_mask is not set.
> Good improvement was observed in the receive side performance when call
> to ath10k_dbg() is avoided in the RX path.
[...]
> +/* Avoid calling __ath10k_dbg() if debug_mask is not set and tracing
> + * disabled.
> + */
> +#define ath10k_dbg(ar, dbg_mask, fmt, ...) \
> +do { \
> + if ((ath10k_debug_mask & dbg_mask) || \
> + trace_ath10k_log_dbg_enabled()) \
> + __ath10k_dbg(ar, dbg_mask, fmt, ##__VA_ARGS__); \
> +} while (0)
Did you consider using jump labels (see include/linux/jump_label.h)?
It's what tracing uses under the hood. I wonder if you could squeeze
out a bit more performance with that? I guess you'd need to add
`struct static_key ath10k_dbg_mask_keys[ATH10K_DBG_MAX]` and re-do
ath10k_debug_mask enum a bit.
Michal
On 4/26/19 6:44 AM, Michał Kazior wrote:
> On Fri, 26 Apr 2019 at 14:58, Venkateswara Naralasetty
> <[email protected]> wrote:
>>
>> ath10k_dbg() is called in ath10k_process_rx() with huge set of arguments
>> which is causing CPU overhead even when debug_mask is not set.
>> Good improvement was observed in the receive side performance when call
>> to ath10k_dbg() is avoided in the RX path.
> [...]
>
>> +/* Avoid calling __ath10k_dbg() if debug_mask is not set and tracing
>> + * disabled.
>> + */
>> +#define ath10k_dbg(ar, dbg_mask, fmt, ...) \
>> +do { \
>> + if ((ath10k_debug_mask & dbg_mask) || \
>> + trace_ath10k_log_dbg_enabled()) \
>> + __ath10k_dbg(ar, dbg_mask, fmt, ##__VA_ARGS__); \
>> +} while (0)
>
> Did you consider using jump labels (see include/linux/jump_label.h)?
> It's what tracing uses under the hood. I wonder if you could squeeze
> out a bit more performance with that? I guess you'd need to add
> `struct static_key ath10k_dbg_mask_keys[ATH10K_DBG_MAX]` and re-do
> ath10k_debug_mask enum a bit.
Maybe first test with debugging just compiled out to see if there is still
any significant overhead with this new patch applied?
Thanks,
Ben
--
Ben Greear <[email protected]>
Candela Technologies Inc http://www.candelatech.com
On 4/26/19 6:38 AM, Venkateswara Naralasetty wrote:
>>> #ifdef CONFIG_ATH10K_DEBUG
>>> -void ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
>>> - const char *fmt, ...)
>>> +void __ath10k_dbg(struct ath10k *ar, enum ath10k_debug_mask mask,
>>> + const char *fmt, ...)
>>> {
>>> struct va_format vaf;
>>> va_list args;
>>
>> Do you still need the check later in this method:
>>
>> if (ath10k_debug_mask & mask)
>>
>> since you already checked in the ath10k_dbg() macro?
> Yes, we need this check.
> Otherwise all debug messages will be printed even without any debug mask set in case of tracing enabled.
Ahh, I see.
Thanks,
Ben
--
Ben Greear <[email protected]>
Candela Technologies Inc http://www.candelatech.com
> -----Original Message-----
> From: ath10k <[email protected]> On Behalf Of Ben
> Greear
> Sent: Friday, April 26, 2019 7:27 PM
> To: Michał Kazior <[email protected]>; Venkateswara Naralasetty
> <[email protected]>
> Cc: Kan Yan <[email protected]>; linux-wireless <linux-
> [email protected]>; [email protected]
> Subject: [EXT] Re: [PATCHv2] ath10k: Add wrapper function to ath10k debug
>
> On 4/26/19 6:44 AM, Michał Kazior wrote:
> > On Fri, 26 Apr 2019 at 14:58, Venkateswara Naralasetty
> > <[email protected]> wrote:
> >>
> >> ath10k_dbg() is called in ath10k_process_rx() with huge set of
> >> arguments which is causing CPU overhead even when debug_mask is not
> set.
> >> Good improvement was observed in the receive side performance when
> >> call to ath10k_dbg() is avoided in the RX path.
> > [...]
> >
> >> +/* Avoid calling __ath10k_dbg() if debug_mask is not set and tracing
> >> + * disabled.
> >> + */
> >> +#define ath10k_dbg(ar, dbg_mask, fmt, ...) \
> >> +do { \
> >> + if ((ath10k_debug_mask & dbg_mask) || \
> >> + trace_ath10k_log_dbg_enabled()) \
> >> + __ath10k_dbg(ar, dbg_mask, fmt, ##__VA_ARGS__); \ }
> >> +while (0)
> >
> > Did you consider using jump labels (see include/linux/jump_label.h)?
> > It's what tracing uses under the hood. I wonder if you could squeeze
> > out a bit more performance with that? I guess you'd need to add
> > `struct static_key ath10k_dbg_mask_keys[ATH10K_DBG_MAX]` and re-do
> > ath10k_debug_mask enum a bit.
>
> Maybe first test with debugging just compiled out to see if there is still any
> significant overhead with this new patch applied?
Since this macro ath10k_dbg defined outside of CONFIG_ATH10K_DEBUG will it make any difference even if debugging compiled out?
Thanks,
Venkatesh.
>
> Thanks,
> Ben
>
> --
> Ben Greear <[email protected]>
> Candela Technologies Inc http://www.candelatech.com
>
>
> _______________________________________________
> ath10k mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/ath10k
> -----Original Message-----
> From: ath10k <[email protected]> On Behalf Of Michal
> Kazior
> Sent: Friday, April 26, 2019 7:15 PM
> To: Venkateswara Naralasetty <[email protected]>
> Cc: Kan Yan <[email protected]>; linux-wireless <linux-
> [email protected]>; [email protected]
> Subject: [EXT] Re: [PATCHv2] ath10k: Add wrapper function to ath10k debug
>
> On Fri, 26 Apr 2019 at 14:58, Venkateswara Naralasetty
> <[email protected]> wrote:
> >
> > ath10k_dbg() is called in ath10k_process_rx() with huge set of
> > arguments which is causing CPU overhead even when debug_mask is not
> set.
> > Good improvement was observed in the receive side performance when
> > call to ath10k_dbg() is avoided in the RX path.
> [...]
>
> > +/* Avoid calling __ath10k_dbg() if debug_mask is not set and tracing
> > + * disabled.
> > + */
> > +#define ath10k_dbg(ar, dbg_mask, fmt, ...) \
> > +do { \
> > + if ((ath10k_debug_mask & dbg_mask) || \
> > + trace_ath10k_log_dbg_enabled()) \
> > + __ath10k_dbg(ar, dbg_mask, fmt, ##__VA_ARGS__); \ }
> > +while (0)
>
> Did you consider using jump labels (see include/linux/jump_label.h)?
> It's what tracing uses under the hood. I wonder if you could squeeze out a bit
> more performance with that? I guess you'd need to add `struct static_key
> ath10k_dbg_mask_keys[ATH10K_DBG_MAX]` and re-do
> ath10k_debug_mask enum a bit.
>
I could not observe any significant Throughput/CPU improvement after using jump labels. For now shall we go with my patch?
Thanks,
Venkatesh.
>
> Michal
>
> _______________________________________________
> ath10k mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/ath10k
Venkateswara Naralasetty <[email protected]> wrote:
> ath10k_dbg() is called in ath10k_process_rx() with huge set of arguments
> which is causing CPU overhead even when debug_mask is not set.
> Good improvement was observed in the receive side performance when call
> to ath10k_dbg() is avoided in the RX path.
>
> Since currently all debug messages are sent via tracing infrastructure,
> we cannot entirely avoid calling ath10k_dbg. Therefore, call to
> ath10k_dbg() is made conditional based on tracing config in the driver.
>
> Trasmit performance remains unchanged with this patch; below are some
> experimental results with this patch and tracing disabled.
>
> mesh mode:
>
> w/o this patch with this patch
> Traffic TP CPU Usage TP CPU usage
>
> TCP 840Mbps 76.53% 960Mbps 78.14%
> UDP 1030Mbps 74.58% 1132Mbps 74.31%
>
> Infra mode:
>
> w/o this patch with this patch
> Traffic TP CPU Usage TP CPU usage
>
> TCP Rx 1241Mbps 80.89% 1270Mbps 73.50%
> UDP Rx 1433Mbps 81.77% 1472Mbps 72.80%
>
> Tested platform : IPQ8064
> hardware used : QCA9984
> firmware ver : ver 10.4-3.5.3-00057
>
> Signed-off-by: Kan Yan <[email protected]>
> Signed-off-by: Venkateswara Naralasetty <[email protected]>
> Signed-off-by: Kalle Valo <[email protected]>
Patch applied to ath-next branch of ath.git, thanks.
9d740d6380e5 ath10k: Add wrapper function to ath10k debug
--
https://patchwork.kernel.org/patch/10919117/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches