[RFC PATCH net-next] sfc: replace in_interrupt() usage
From: Edward Cree <hidden>
Date: 2020-09-28 20:11:17
Also in:
lkml
Subsystem:
networking drivers, sfc network driver, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Edward Cree, Linus Torvalds
efx_ef10_try_update_nic_stats_vf() used in_interrupt() to figure out
whether it is safe to sleep (for MCDI) or not.
The only caller from which it was not is efx_net_stats(), which can be
invoked under dev_base_lock from net-sysfs::netstat_show().
So add a new update_stats_atomic() method to struct efx_nic_type, and
call it from efx_net_stats(), removing the need for
efx_ef10_try_update_nic_stats_vf() to behave differently for this case
(which it wasn't doing correctly anyway).
For all nic_types other than EF10 VF, this method is NULL and so we
call the regular update_stats() methods, which are happy with being
called from atomic contexts.
Fixes: f00bf2305cab ("sfc: don't update stats on VF when called in atomic context")
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Edward Cree <redacted>
---
Only compile-tested so far, because I'm waiting for my kernel to
finish rebuilding with CONFIG_DEBUG_ATOMIC_SLEEP which I'm hoping
is the right thing to detect the bug in the existing code.
I also wasn't quite sure how to give credit to the thorough analysis
in the commit message of Sebastian's patch. I don't think we have
a Whatever-by: tag to cover that, do we?
And this doesn't include your GFP_KERNEL change, which should
probably go in separately if you take this.
drivers/net/ethernet/sfc/ef10.c | 22 +++++++++++++---------
drivers/net/ethernet/sfc/efx_common.c | 2 +-
drivers/net/ethernet/sfc/net_driver.h | 5 +++++
drivers/net/ethernet/sfc/nic_common.h | 7 +++++++
4 files changed, 26 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index c9df2e96ebe4..b702ba5986dc 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c@@ -1871,15 +1871,6 @@ static int efx_ef10_try_update_nic_stats_vf(struct efx_nic *efx) spin_unlock_bh(&efx->stats_lock); - if (in_interrupt()) { - /* If in atomic context, cannot update stats. Just update the - * software stats and return so the caller can continue. - */ - spin_lock_bh(&efx->stats_lock); - efx_update_sw_stats(efx, stats); - return 0; - } - efx_ef10_get_stat_mask(efx, mask); rc = efx_nic_alloc_buffer(efx, &stats_buf, dma_len, GFP_ATOMIC);
@@ -1938,6 +1929,18 @@ static size_t efx_ef10_update_stats_vf(struct efx_nic *efx, u64 *full_stats, return efx_ef10_update_stats_common(efx, full_stats, core_stats); } +static size_t efx_ef10_update_stats_atomic_vf(struct efx_nic *efx, u64 *full_stats, + struct rtnl_link_stats64 *core_stats) +{ + struct efx_ef10_nic_data *nic_data = efx->nic_data; + + /* In atomic context, cannot update HW stats. Just update the + * software stats and return so the caller can continue. + */ + efx_update_sw_stats(efx, nic_data->stats); + return efx_ef10_update_stats_common(efx, full_stats, core_stats); +} + static void efx_ef10_push_irq_moderation(struct efx_channel *channel) { struct efx_nic *efx = channel->efx;
@@ -3998,6 +4001,7 @@ const struct efx_nic_type efx_hunt_a0_vf_nic_type = { .finish_flr = efx_port_dummy_op_void, .describe_stats = efx_ef10_describe_stats, .update_stats = efx_ef10_update_stats_vf, + .update_stats_atomic = efx_ef10_update_stats_atomic_vf, .start_stats = efx_port_dummy_op_void, .pull_stats = efx_port_dummy_op_void, .stop_stats = efx_port_dummy_op_void,
diff --git a/drivers/net/ethernet/sfc/efx_common.c b/drivers/net/ethernet/sfc/efx_common.c
index c256db241570..72a3f0e09f52 100644
--- a/drivers/net/ethernet/sfc/efx_common.c
+++ b/drivers/net/ethernet/sfc/efx_common.c@@ -602,7 +602,7 @@ void efx_net_stats(struct net_device *net_dev, struct rtnl_link_stats64 *stats) struct efx_nic *efx = netdev_priv(net_dev); spin_lock_bh(&efx->stats_lock); - efx->type->update_stats(efx, NULL, stats); + efx_nic_update_stats_atomic(efx, NULL, stats); spin_unlock_bh(&efx->stats_lock); }
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 47aa753e64bd..9f7dfdf708cf 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h@@ -1172,6 +1172,9 @@ struct efx_udp_tunnel { * @describe_stats: Describe statistics for ethtool * @update_stats: Update statistics not provided by event handling. * Either argument may be %NULL. + * @update_stats_atomic: Update statistics while in atomic context, if that + * is more limiting than @update_stats. Otherwise, leave %NULL and + * driver core will call @update_stats. * @start_stats: Start the regular fetching of statistics * @pull_stats: Pull stats from the NIC and wait until they arrive. * @stop_stats: Stop the regular fetching of statistics
@@ -1316,6 +1319,8 @@ struct efx_nic_type { size_t (*describe_stats)(struct efx_nic *efx, u8 *names); size_t (*update_stats)(struct efx_nic *efx, u64 *full_stats, struct rtnl_link_stats64 *core_stats); + size_t (*update_stats_atomic)(struct efx_nic *efx, u64 *full_stats, + struct rtnl_link_stats64 *core_stats); void (*start_stats)(struct efx_nic *efx); void (*pull_stats)(struct efx_nic *efx); void (*stop_stats)(struct efx_nic *efx);
diff --git a/drivers/net/ethernet/sfc/nic_common.h b/drivers/net/ethernet/sfc/nic_common.h
index 82271f0b8627..b9cafe9cd568 100644
--- a/drivers/net/ethernet/sfc/nic_common.h
+++ b/drivers/net/ethernet/sfc/nic_common.h@@ -244,6 +244,13 @@ void efx_nic_update_stats(const struct efx_hw_stat_desc *desc, size_t count, const unsigned long *mask, u64 *stats, const void *dma_buf, bool accumulate); void efx_nic_fix_nodesc_drop_stat(struct efx_nic *efx, u64 *stat); +static inline size_t efx_nic_update_stats_atomic(struct efx_nic *efx, u64 *full_stats, + struct rtnl_link_stats64 *core_stats) +{ + if (efx->type->update_stats_atomic) + return efx->type->update_stats_atomic(efx, full_stats, core_stats); + return efx->type->update_stats(efx, full_stats, core_stats); +} #define EFX_MAX_FLUSH_TIME 5000