From 98a3b2fe435ae76170936c14f5c9e6a87548e3ef Mon Sep 17 00:00:00 2001
From: Michael Buesch <mb@bu3sch.de>
Date: Thu, 12 Jun 2008 12:36:29 +0200
Subject: [PATCH] b43: Fix noise calculation WARN_ON
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.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
---
drivers/net/wireless/b43/b43.h | 1 -
drivers/net/wireless/b43/main.c | 16 ++++++++++------
2 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/net/wireless/b43/b43.h b/drivers/net/wireless/b43/b43.h
index dfa4bdd5597c..d3db298c05fc 100644
--- a/drivers/net/wireless/b43/b43.h
+++ b/drivers/net/wireless/b43/b43.h
@@ -630,7 +630,6 @@ struct b43_pio {
/* 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];
diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c
index 6c3d9ea0a9f8..fa4b0d8b74a2 100644
--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -1145,7 +1145,6 @@ 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)
@@ -1154,7 +1153,6 @@ static void b43_calculate_link_quality(struct b43_wldev *dev)
if (dev->noisecalc.calculation_running)
return;
- dev->noisecalc.channel_at_start = dev->phy.channel;
dev->noisecalc.calculation_running = 1;
dev->noisecalc.nr_samples = 0;
@@ -1171,9 +1169,16 @@ static void handle_irq_noise(struct b43_wldev *dev)
/* 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)
@@ -1214,11 +1219,10 @@ static void handle_irq_noise(struct b43_wldev *dev)
average -= 48;
dev->stats.link_noise = average;
- drop_calculation:
dev->noisecalc.calculation_running = 0;
return;
}
- generate_new:
+generate_new:
b43_generate_noise_sample(dev);
}
--
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