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mac80211: compute chanctx refcount on-the-fly
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It doesn't make much sense to store refcount in
the chanctx structure. One still needs to hold
chanctx_mtx to get the value safely. Besides,
refcount isn't on performance critical paths.

This will make implementing chanctx reservation
refcounting a little easier.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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Michal Kazior authored and Johannes Berg committed Apr 25, 2014
1 parent 2b32713 commit c0166da
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Showing 4 changed files with 49 additions and 17 deletions.
2 changes: 1 addition & 1 deletion net/mac80211/cfg.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3251,7 +3251,7 @@ int ieee80211_channel_switch(struct wiphy *wiphy, struct net_device *dev,

/* don't handle for multi-VIF cases */
chanctx = container_of(conf, struct ieee80211_chanctx, conf);
if (chanctx->refcount > 1) {
if (ieee80211_chanctx_refcount(local, chanctx) > 1) {
mutex_unlock(&local->chanctx_mtx);
return -EBUSY;
}
Expand Down
59 changes: 45 additions & 14 deletions net/mac80211/chan.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,41 @@
#include "ieee80211_i.h"
#include "driver-ops.h"

static int ieee80211_chanctx_num_assigned(struct ieee80211_local *local,
struct ieee80211_chanctx *ctx)
{
struct ieee80211_sub_if_data *sdata;
int num = 0;

lockdep_assert_held(&local->chanctx_mtx);

list_for_each_entry(sdata, &ctx->assigned_vifs, assigned_chanctx_list)
num++;

return num;
}

static int ieee80211_chanctx_num_reserved(struct ieee80211_local *local,
struct ieee80211_chanctx *ctx)
{
struct ieee80211_sub_if_data *sdata;
int num = 0;

lockdep_assert_held(&local->chanctx_mtx);

list_for_each_entry(sdata, &ctx->reserved_vifs, reserved_chanctx_list)
num++;

return num;
}

int ieee80211_chanctx_refcount(struct ieee80211_local *local,
struct ieee80211_chanctx *ctx)
{
return ieee80211_chanctx_num_assigned(local, ctx) +
ieee80211_chanctx_num_reserved(local, ctx);
}

static int ieee80211_num_chanctx(struct ieee80211_local *local)
{
struct ieee80211_chanctx *ctx;
Expand Down Expand Up @@ -463,7 +498,7 @@ static void ieee80211_free_chanctx(struct ieee80211_local *local,
{
lockdep_assert_held(&local->chanctx_mtx);

WARN_ON_ONCE(ctx->refcount != 0);
WARN_ON_ONCE(ieee80211_chanctx_refcount(local, ctx) != 0);

list_del_rcu(&ctx->list);
ieee80211_del_chanctx(local, ctx);
Expand Down Expand Up @@ -542,7 +577,6 @@ static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
if (conf) {
curr_ctx = container_of(conf, struct ieee80211_chanctx, conf);

curr_ctx->refcount--;
drv_unassign_vif_chanctx(local, sdata, curr_ctx);
conf = NULL;
list_del(&sdata->assigned_chanctx_list);
Expand All @@ -553,7 +587,6 @@ static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,
if (ret)
goto out;

new_ctx->refcount++;
conf = &new_ctx->conf;
list_add(&sdata->assigned_chanctx_list,
&new_ctx->assigned_vifs);
Expand All @@ -564,14 +597,14 @@ static int ieee80211_assign_vif_chanctx(struct ieee80211_sub_if_data *sdata,

sdata->vif.bss_conf.idle = !conf;

if (curr_ctx && curr_ctx->refcount > 0) {
if (curr_ctx && ieee80211_chanctx_num_assigned(local, curr_ctx) > 0) {
ieee80211_recalc_chanctx_chantype(local, curr_ctx);
ieee80211_recalc_smps_chanctx(local, curr_ctx);
ieee80211_recalc_radar_chanctx(local, curr_ctx);
ieee80211_recalc_chanctx_min_def(local, curr_ctx);
}

if (new_ctx && new_ctx->refcount > 0) {
if (new_ctx && ieee80211_chanctx_num_assigned(local, new_ctx) > 0) {
ieee80211_recalc_txpower(sdata);
ieee80211_recalc_chanctx_min_def(local, new_ctx);
}
Expand Down Expand Up @@ -603,7 +636,7 @@ static void __ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
ieee80211_vif_unreserve_chanctx(sdata);

ieee80211_assign_vif_chanctx(sdata, NULL);
if (ctx->refcount == 0)
if (ieee80211_chanctx_refcount(local, ctx) == 0)
ieee80211_free_chanctx(local, ctx);
}

Expand Down Expand Up @@ -735,7 +768,7 @@ int ieee80211_vif_use_channel(struct ieee80211_sub_if_data *sdata,
ret = ieee80211_assign_vif_chanctx(sdata, ctx);
if (ret) {
/* if assign fails refcount stays the same */
if (ctx->refcount == 0)
if (ieee80211_chanctx_refcount(local, ctx) == 0)
ieee80211_free_chanctx(local, ctx);
goto out;
}
Expand All @@ -759,7 +792,7 @@ static int __ieee80211_vif_change_channel(struct ieee80211_sub_if_data *sdata,
IEEE80211_CHAN_DISABLED))
return -EINVAL;

if (ctx->refcount != 1)
if (ieee80211_chanctx_refcount(local, ctx) != 1)
return -EINVAL;

if (sdata->vif.bss_conf.chandef.width != chandef->width) {
Expand Down Expand Up @@ -865,7 +898,7 @@ int ieee80211_vif_unreserve_chanctx(struct ieee80211_sub_if_data *sdata)
list_del(&sdata->reserved_chanctx_list);
sdata->reserved_chanctx = NULL;

if (--ctx->refcount == 0)
if (ieee80211_chanctx_refcount(sdata->local, ctx) == 0)
ieee80211_free_chanctx(sdata->local, ctx);

return 0;
Expand Down Expand Up @@ -894,7 +927,7 @@ int ieee80211_vif_reserve_chanctx(struct ieee80211_sub_if_data *sdata,

new_ctx = ieee80211_find_reservation_chanctx(local, chandef, mode);
if (!new_ctx) {
if (curr_ctx->refcount == 1 &&
if (ieee80211_chanctx_refcount(local, curr_ctx) == 1 &&
(local->hw.flags & IEEE80211_HW_CHANGE_RUNNING_CHANCTX)) {
/* if we're the only users of the chanctx and
* the driver supports changing a running
Expand All @@ -915,7 +948,6 @@ int ieee80211_vif_reserve_chanctx(struct ieee80211_sub_if_data *sdata,
}

list_add(&sdata->reserved_chanctx_list, &new_ctx->reserved_vifs);
new_ctx->refcount++;
sdata->reserved_chanctx = new_ctx;
sdata->reserved_chandef = *chandef;
sdata->reserved_radar_required = radar_required;
Expand Down Expand Up @@ -961,7 +993,6 @@ int ieee80211_vif_use_reserved_context(struct ieee80211_sub_if_data *sdata,
sdata->vif.bss_conf.chandef = sdata->reserved_chandef;

/* unref our reservation */
ctx->refcount--;
sdata->reserved_chanctx = NULL;
sdata->radar_required = sdata->reserved_radar_required;
list_del(&sdata->reserved_chanctx_list);
Expand All @@ -974,11 +1005,11 @@ int ieee80211_vif_use_reserved_context(struct ieee80211_sub_if_data *sdata,
goto out;
} else {
ret = ieee80211_assign_vif_chanctx(sdata, ctx);
if (old_ctx->refcount == 0)
if (ieee80211_chanctx_refcount(local, old_ctx) == 0)
ieee80211_free_chanctx(local, old_ctx);
if (ret) {
/* if assign fails refcount stays the same */
if (ctx->refcount == 0)
if (ieee80211_chanctx_refcount(local, ctx) == 0)
ieee80211_free_chanctx(local, ctx);
goto out;
}
Expand Down
3 changes: 2 additions & 1 deletion net/mac80211/ieee80211_i.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -695,7 +695,6 @@ struct ieee80211_chanctx {
struct list_head reserved_vifs;

enum ieee80211_chanctx_mode mode;
int refcount;
bool driver_present;

struct ieee80211_chanctx_conf conf;
Expand Down Expand Up @@ -1803,6 +1802,8 @@ void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata);
void ieee80211_vif_vlan_copy_chanctx(struct ieee80211_sub_if_data *sdata);
void ieee80211_vif_copy_chanctx_to_vlans(struct ieee80211_sub_if_data *sdata,
bool clear);
int ieee80211_chanctx_refcount(struct ieee80211_local *local,
struct ieee80211_chanctx *ctx);

void ieee80211_recalc_smps_chanctx(struct ieee80211_local *local,
struct ieee80211_chanctx *chanctx);
Expand Down
2 changes: 1 addition & 1 deletion net/mac80211/mlme.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1089,7 +1089,7 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
}
chanctx = container_of(rcu_access_pointer(sdata->vif.chanctx_conf),
struct ieee80211_chanctx, conf);
if (chanctx->refcount > 1) {
if (ieee80211_chanctx_refcount(local, chanctx) > 1) {
sdata_info(sdata,
"channel switch with multiple interfaces on the same channel, disconnecting\n");
ieee80211_queue_work(&local->hw,
Expand Down

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