From: Vladimir Oltean olteanv@gmail.com
[ Upstream commit 3e8db7e56082156a37b71d7334860c10fcea8025 ]
Currently this stack trace can be seen with CONFIG_DEBUG_ATOMIC_SLEEP=y:
[ 41.568348] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:909 [ 41.576757] in_atomic(): 1, irqs_disabled(): 0, pid: 208, name: ptp4l [ 41.583212] INFO: lockdep is turned off. [ 41.587123] CPU: 1 PID: 208 Comm: ptp4l Not tainted 5.3.0-rc6-01445-ge950f2d4bc7f-dirty #1827 [ 41.599873] [<c0313d7c>] (unwind_backtrace) from [<c030e13c>] (show_stack+0x10/0x14) [ 41.607584] [<c030e13c>] (show_stack) from [<c1212d50>] (dump_stack+0xd4/0x100) [ 41.614863] [<c1212d50>] (dump_stack) from [<c037dfc8>] (___might_sleep+0x1c8/0x2b4) [ 41.622574] [<c037dfc8>] (___might_sleep) from [<c122ea90>] (__mutex_lock+0x48/0xab8) [ 41.630368] [<c122ea90>] (__mutex_lock) from [<c122f51c>] (mutex_lock_nested+0x1c/0x24) [ 41.638340] [<c122f51c>] (mutex_lock_nested) from [<c0c6fe08>] (sja1105_static_config_reload+0x30/0x27c) [ 41.647779] [<c0c6fe08>] (sja1105_static_config_reload) from [<c0c7015c>] (sja1105_hwtstamp_set+0x108/0x1cc) [ 41.657562] [<c0c7015c>] (sja1105_hwtstamp_set) from [<c0feb650>] (dev_ifsioc+0x18c/0x330) [ 41.665788] [<c0feb650>] (dev_ifsioc) from [<c0febbd8>] (dev_ioctl+0x320/0x6e8) [ 41.673064] [<c0febbd8>] (dev_ioctl) from [<c0f8b1f4>] (sock_ioctl+0x334/0x5e8) [ 41.680340] [<c0f8b1f4>] (sock_ioctl) from [<c05404a8>] (do_vfs_ioctl+0xb0/0xa10) [ 41.687789] [<c05404a8>] (do_vfs_ioctl) from [<c0540e3c>] (ksys_ioctl+0x34/0x58) [ 41.695151] [<c0540e3c>] (ksys_ioctl) from [<c0301000>] (ret_fast_syscall+0x0/0x28) [ 41.702768] Exception stack(0xe8495fa8 to 0xe8495ff0) [ 41.707796] 5fa0: beff4a8c 00000001 00000011 000089b0 beff4a8c beff4a80 [ 41.715933] 5fc0: beff4a8c 00000001 0000000c 00000036 b6fa98c8 004e19c1 00000001 00000000 [ 41.724069] 5fe0: 004dcedc beff4a6c 004c0738 b6e7af4c [ 41.729860] BUG: scheduling while atomic: ptp4l/208/0x00000002 [ 41.735682] INFO: lockdep is turned off.
Enabling RX timestamping will logically disturb the fastpath (processing of meta frames). Replace bool hwts_rx_en with a bit that is checked atomically from the fastpath and temporarily unset from the sleepable context during a change of the RX timestamping process (a destructive operation anyways, requires switch reset). If found unset, the fastpath (net/dsa/tag_sja1105.c) will just drop any received meta frame and not take the meta_lock at all.
Fixes: a602afd200f5 ("net: dsa: sja1105: Expose PTP timestamping ioctls to userspace") Signed-off-by: Vladimir Oltean olteanv@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/dsa/sja1105/sja1105_main.c | 19 +++++++++++-------- include/linux/dsa/sja1105.h | 4 +++- net/dsa/tag_sja1105.c | 12 +++++++++++- 3 files changed, 25 insertions(+), 10 deletions(-)
--- a/drivers/net/dsa/sja1105/sja1105_main.c +++ b/drivers/net/dsa/sja1105/sja1105_main.c @@ -1875,7 +1875,9 @@ static int sja1105_set_ageing_time(struc return sja1105_static_config_reload(priv); }
-/* Caller must hold priv->tagger_data.meta_lock */ +/* Must be called only with priv->tagger_data.state bit + * SJA1105_HWTS_RX_EN cleared + */ static int sja1105_change_rxtstamping(struct sja1105_private *priv, bool on) { @@ -1932,16 +1934,17 @@ static int sja1105_hwtstamp_set(struct d break; }
- if (rx_on != priv->tagger_data.hwts_rx_en) { - spin_lock(&priv->tagger_data.meta_lock); + if (rx_on != test_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state)) { + clear_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state); + rc = sja1105_change_rxtstamping(priv, rx_on); - spin_unlock(&priv->tagger_data.meta_lock); if (rc < 0) { dev_err(ds->dev, "Failed to change RX timestamping: %d\n", rc); - return -EFAULT; + return rc; } - priv->tagger_data.hwts_rx_en = rx_on; + if (rx_on) + set_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state); }
if (copy_to_user(ifr->ifr_data, &config, sizeof(config))) @@ -1960,7 +1963,7 @@ static int sja1105_hwtstamp_get(struct d config.tx_type = HWTSTAMP_TX_ON; else config.tx_type = HWTSTAMP_TX_OFF; - if (priv->tagger_data.hwts_rx_en) + if (test_bit(SJA1105_HWTS_RX_EN, &priv->tagger_data.state)) config.rx_filter = HWTSTAMP_FILTER_PTP_V2_L2_EVENT; else config.rx_filter = HWTSTAMP_FILTER_NONE; @@ -2009,7 +2012,7 @@ static bool sja1105_port_rxtstamp(struct struct sja1105_private *priv = ds->priv; struct sja1105_tagger_data *data = &priv->tagger_data;
- if (!data->hwts_rx_en) + if (!test_bit(SJA1105_HWTS_RX_EN, &data->state)) return false;
/* We need to read the full PTP clock to reconstruct the Rx --- a/include/linux/dsa/sja1105.h +++ b/include/linux/dsa/sja1105.h @@ -31,6 +31,8 @@ #define SJA1105_META_SMAC 0x222222222222ull #define SJA1105_META_DMAC 0x0180C200000Eull
+#define SJA1105_HWTS_RX_EN 0 + /* Global tagger data: each struct sja1105_port has a reference to * the structure defined in struct sja1105_private. */ @@ -42,7 +44,7 @@ struct sja1105_tagger_data { * from taggers running on multiple ports on SMP systems */ spinlock_t meta_lock; - bool hwts_rx_en; + unsigned long state; };
struct sja1105_skb_cb { --- a/net/dsa/tag_sja1105.c +++ b/net/dsa/tag_sja1105.c @@ -155,7 +155,11 @@ static struct sk_buff /* Step 1: A timestampable frame was received. * Buffer it until we get its meta frame. */ - if (is_link_local && sp->data->hwts_rx_en) { + if (is_link_local) { + if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state)) + /* Do normal processing. */ + return skb; + spin_lock(&sp->data->meta_lock); /* Was this a link-local frame instead of the meta * that we were expecting? @@ -186,6 +190,12 @@ static struct sk_buff } else if (is_meta) { struct sk_buff *stampable_skb;
+ /* Drop the meta frame if we're not in the right state + * to process it. + */ + if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state)) + return NULL; + spin_lock(&sp->data->meta_lock);
stampable_skb = sp->data->stampable_skb;