This removes a WARN_ON that is responsible for the following koops:
http://www.kerneloops.org/searchweek.php?search=b43_generate_noise_sample
The comment in the patch describes why it's safe to simply remove
the check.
This patch is upstream in John Linville's wireless-testing.git tree
as commit 86ef1ae07289c9f0aa1aa310d43653e513e6f124
Signed-off-by: Michael Buesch <[EMAIL PROTECTED]>
Index: linux-2.6.25.6/drivers/net/wireless/b43/b43.h
===
--- linux-2.6.25.6.orig/drivers/net/wireless/b43/b43.h 2008-06-14
22:43:28.0 +0200
+++ linux-2.6.25.6/drivers/net/wireless/b43/b43.h 2008-06-14
22:47:02.0 +0200
@@ -593,13 +593,12 @@ struct b43_dma {
struct b43_dmaring *rx_ring0;
struct b43_dmaring *rx_ring3; /* only available on core.rev < 5 */
};
/* Context information for a noise calculation (Link Quality). */
struct b43_noise_calculation {
- u8 channel_at_start;
bool calculation_running;
u8 nr_samples;
s8 samples[8][4];
};
struct b43_stats {
Index: linux-2.6.25.6/drivers/net/wireless/b43/main.c
===
--- linux-2.6.25.6.orig/drivers/net/wireless/b43/main.c 2008-06-14
22:44:16.0 +0200
+++ linux-2.6.25.6/drivers/net/wireless/b43/main.c 2008-06-14
22:47:02.0 +0200
@@ -1024,22 +1024,20 @@ static void b43_jssi_write(struct b43_wl
static void b43_generate_noise_sample(struct b43_wldev *dev)
{
b43_jssi_write(dev, 0x7F7F7F7F);
b43_write32(dev, B43_MMIO_MACCMD,
b43_read32(dev, B43_MMIO_MACCMD) | B43_MACCMD_BGNOISE);
- B43_WARN_ON(dev->noisecalc.channel_at_start != dev->phy.channel);
}
static void b43_calculate_link_quality(struct b43_wldev *dev)
{
/* Top half of Link Quality calculation. */
if (dev->noisecalc.calculation_running)
return;
- dev->noisecalc.channel_at_start = dev->phy.channel;
dev->noisecalc.calculation_running = 1;
dev->noisecalc.nr_samples = 0;
b43_generate_noise_sample(dev);
}
@@ -1050,15 +1048,22 @@ static void handle_irq_noise(struct b43_
u8 noise[4];
u8 i, j;
s32 average;
/* Bottom half of Link Quality calculation. */
+ /* Possible race condition: It might be possible that the user
+* changed to a different channel in the meantime since we
+* started the calculation. We ignore that fact, since it's
+* not really that much of a problem. The background noise is
+* an estimation only anyway. Slightly wrong results will get damped
+* by the averaging of the 8 sample rounds. Additionally the
+* value is shortlived. So it will be replaced by the next noise
+* calculation round soon. */
+
B43_WARN_ON(!dev->noisecalc.calculation_running);
- if (dev->noisecalc.channel_at_start != phy->channel)
- goto drop_calculation;
*((__le32 *)noise) = cpu_to_le32(b43_jssi_read(dev));
if (noise[0] == 0x7F || noise[1] == 0x7F ||
noise[2] == 0x7F || noise[3] == 0x7F)
goto generate_new;
/* Get the noise samples. */
@@ -1093,17 +1098,16 @@ static void handle_irq_noise(struct b43_
if (tmp == 8)
average -= 72;
else
average -= 48;
dev->stats.link_noise = average;
- drop_calculation:
dev->noisecalc.calculation_running = 0;
return;
}
- generate_new:
+generate_new:
b43_generate_noise_sample(dev);
}
static void handle_irq_tbtt_indication(struct b43_wldev *dev)
{
if (b43_is_mode(dev->wl, IEEE80211_IF_TYPE_AP)) {
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