Re: [RFC] trace-cmd: plugin_mac80211: add parsing for the new drv_switch_vif_chanctx

[Johannes Berg <johannes@sipsolutions.net>]

Steven, what do you think about those packed structs in a dynamic
array? I've applied the kernel patch but I can still back it out if you
know of a better solution.

Thanks,
johannes

On Fri, 2014-05-23 at 22:30 +0300, Luca Coelho wrote:
> From: Luciano Coelho <luciano.coelho@intel.com>
> 
> This new command has a complex trace, with a variable number of struct
> elements in an array and needs special parsing.  Add a parsing
> function to handle it.
> 
> Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
> ---
>  I'm sending this to linux-wireless as an RFC before sending it to
> Steven to get some comments and because the new function hasn't yet
> gotten to linux-wireless/mainline.
> 
>  plugin_mac80211.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 93 insertions(+)
> 
> diff --git a/plugin_mac80211.c b/plugin_mac80211.c
> index f35cb80..0b4835e 100644
> --- a/plugin_mac80211.c
> +++ b/plugin_mac80211.c
> @@ -191,12 +191,105 @@ static int drv_config(struct trace_seq *s, struct pevent_record *record,
>  	return 0;
>  }
>  
> +struct trace_vif_entry {
> +	int vif_type;

This in particular was an enum upstream - which technically doesn't n

> +	bool p2p;
> +	char vif_name[8];
> +} __attribute__((packed));
> +
> +struct trace_chandef_entry {
> +	unsigned int control_freq;
> +	unsigned int chan_width;
> +	unsigned int center_freq1;
> +	unsigned int center_freq2;
> +} __attribute__((packed));
> +
> +struct trace_switch_entry {
> +	struct trace_vif_entry vif;
> +	struct trace_chandef_entry old_chandef;
> +	struct trace_chandef_entry new_chandef;
> +} __attribute__((packed));
> +
> +static int drv_switch_vif_chanctx(struct trace_seq *s,
> +				  struct pevent_record *record,
> +				  struct event_format *event, void *context)
> +{
> +	struct format_field *f = pevent_find_field(event, "n_vifs");
> +	unsigned int i, offset, len;
> +	long long unsigned int n_vifs;
> +	void *data = record->data;
> +	struct trace_switch_entry *vifs;
> +
> +	if (!f) {
> +		trace_seq_printf(s, "NOTFOUND: n_vifs");
> +		return 0;
> +	}
> +
> +	if (pevent_read_number_field(f, data, &n_vifs)) {
> +		trace_seq_puts(s, "field-invalid: n_vifs");
> +		return 0;
> +	}
> +
> +	f = pevent_find_field(event, "vifs");
> +
> +	if (!f) {
> +		trace_seq_printf(s, "NOTFOUND: vifs");
> +		return 0;
> +	}
> +
> +	offset = f->offset;
> +	len = f->size;
> +	if (f->flags & FIELD_IS_DYNAMIC) {
> +		long long unsigned int val;
> +
> +		val = pevent_read_number(event->pevent, data + offset, len);
> +		offset = val;
> +		len = offset >> 16;
> +		offset &= 0xffff;
> +	}
> +
> +	if (len != sizeof(*vifs) * n_vifs) {
> +		trace_seq_printf(s, "field-invalid: vifs");
> +		return 0;
> +	}
> +
> +	print_string(s, event, "wiphy_name", data);
> +	pevent_print_num_field(s, " n_vifs:%d ", event, "n_vifs", record, 1);
> +	print_enum(s, event, "mode", data,
> +		   { 0, "REASSIGN_VIF" },
> +		   { 1, "SWAP_CONTEXTS"} );
> +
> +	vifs = (void *) (char *) data + offset;
> +
> +	for (i = 0; i < n_vifs; i++) {
> +		trace_seq_printf(s, "\n%*s\t", INDENT, "");
> +		trace_seq_printf(s, "vif %d:\tname: %s type: %d p2p: %d",
> +				 i, vifs[i].vif.vif_name, vifs[i].vif.vif_type,
> +				 vifs[i].vif.p2p);
> +		trace_seq_printf(s, "\n%*s\t\t", INDENT, "");
> +		trace_seq_printf(s, "old_ctx: control_freq: %d chan_width: %d center_freq1: %d center_freq2: %d",
> +				 vifs[i].old_chandef.control_freq,
> +				 vifs[i].old_chandef.chan_width,
> +				 vifs[i].old_chandef.center_freq1,
> +				 vifs[i].old_chandef.center_freq2);
> +		trace_seq_printf(s, "\n%*s\t\t", INDENT, "");
> +		trace_seq_printf(s, "new_ctx: control_freq: %d chan_width: %d center_freq1: %d center_freq2: %d",
> +				 vifs[i].new_chandef.control_freq,
> +				 vifs[i].new_chandef.chan_width,
> +				 vifs[i].new_chandef.center_freq1,
> +				 vifs[i].new_chandef.center_freq2);
> +	}
> +
> +	return 0;
> +}
>  int PEVENT_PLUGIN_LOADER(struct pevent *pevent)
>  {
>  	pevent_register_event_handler(pevent, -1, "mac80211", "drv_bss_info_changed",
>  				      drv_bss_info_changed, NULL);
>  	pevent_register_event_handler(pevent, -1, "mac80211", "drv_config",
>  				      drv_config, NULL);
> +	pevent_register_event_handler(pevent, -1, "mac80211", "drv_switch_vif_chanctx",
> +				      drv_switch_vif_chanctx, NULL);
>  
>  	return 0;
>  }