[PATCH 5.15 2/2] octeontx2-pf: Fix the use of GFP_KERNEL in atomic context on rt

Kevin Hao
2023-01-22T22:52:50Z

commit 55ba18dc62deff5910c0fa64486dea1ff20832ff upstream.

The commit 4af1b64f80fb ("octeontx2-pf: Fix lmtst ID used in aura
free") uses the get/put_cpu() to protect the usage of percpu pointer
in ->aura_freeptr() callback, but it also unnecessarily disable the
preemption for the blockable memory allocation. The commit 87b93b678e95
("octeontx2-pf: Avoid use of GFP_KERNEL in atomic context") tried to
fix these sleep inside atomic warnings. But it only fix the one for
the non-rt kernel. For the rt kernel, we still get the similar warnings
like below.
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0
preempt_count: 1, expected: 0
RCU nest depth: 0, expected: 0
3 locks held by swapper/0/1:
#0: ffff800009fc5fe8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x24/0x30
#1: ffff000100c276c0 (&mbox->lock){+.+.}-{3:3}, at: otx2_init_hw_resources+0x8c/0x3a4
#2: ffffffbfef6537e0 (&cpu_rcache->lock){+.+.}-{2:2}, at: alloc_iova_fast+0x1ac/0x2ac
Preemption disabled at:
[<ffff800008b1908c>] otx2_rq_aura_pool_init+0x14c/0x284
CPU: 20 PID: 1 Comm: swapper/0 Tainted: G W 6.2.0-rc3-rt1-yocto-preempt-rt #1
Hardware name: Marvell OcteonTX CN96XX board (DT)
Call trace:
dump_backtrace.part.0+0xe8/0xf4
show_stack+0x20/0x30
dump_stack_lvl+0x9c/0xd8
dump_stack+0x18/0x34
__might_resched+0x188/0x224
rt_spin_lock+0x64/0x110
alloc_iova_fast+0x1ac/0x2ac
iommu_dma_alloc_iova+0xd4/0x110
__iommu_dma_map+0x80/0x144
iommu_dma_map_page+0xe8/0x260
dma_map_page_attrs+0xb4/0xc0
__otx2_alloc_rbuf+0x90/0x150
otx2_rq_aura_pool_init+0x1c8/0x284
otx2_init_hw_resources+0xe4/0x3a4
otx2_open+0xf0/0x610
__dev_open+0x104/0x224
__dev_change_flags+0x1e4/0x274
dev_change_flags+0x2c/0x7c
ic_open_devs+0x124/0x2f8
ip_auto_config+0x180/0x42c
do_one_initcall+0x90/0x4dc
do_basic_setup+0x10c/0x14c
kernel_init_freeable+0x10c/0x13c
kernel_init+0x2c/0x140
ret_from_fork+0x10/0x20

Of course, we can shuffle the get/put_cpu() to only wrap the invocation
of ->aura_freeptr() as what commit 87b93b678e95 does. But there are only
two ->aura_freeptr() callbacks, otx2_aura_freeptr() and
cn10k_aura_freeptr(). There is no usage of perpcu variable in the
otx2_aura_freeptr() at all, so the get/put_cpu() seems redundant to it.
We can move the get/put_cpu() into the corresponding callback which
really has the percpu variable usage and avoid the sprinkling of
get/put_cpu() in several places.

Fixes: 4af1b64f80fb ("octeontx2-pf: Fix lmtst ID used in aura free")
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Link: https://lore.kernel.org/r/20230118071300.3271125-1-haokexin@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
.../net/ethernet/marvell/octeontx2/nic/otx2_common.c | 11 ++---------
.../net/ethernet/marvell/octeontx2/nic/otx2_common.h | 2 ++
2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
index 30d4c0ad712d..2e225309de9c 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
@@ -962,7 +962,6 @@ static void otx2_pool_refill_task(struct work_struct *work)
rbpool = cq->rbpool;
free_ptrs = cq->pool_ptrs;

- get_cpu();
while (cq->pool_ptrs) {
if (otx2_alloc_rbuf(pfvf, rbpool, &bufptr)) {
/* Schedule a WQ if we fails to free atleast half of the
@@ -982,7 +981,6 @@ static void otx2_pool_refill_task(struct work_struct *work)
pfvf->hw_ops->aura_freeptr(pfvf, qidx, bufptr + OTX2_HEAD_ROOM);
cq->pool_ptrs--;
}
- put_cpu();
cq->refill_task_sched = false;
}

@@ -1333,9 +1331,7 @@ int otx2_sq_aura_pool_init(struct otx2_nic *pfvf)
err = otx2_alloc_rbuf(pfvf, pool, &bufptr);
if (err)
goto err_mem;
- get_cpu();
pfvf->hw_ops->aura_freeptr(pfvf, pool_id, bufptr);
- put_cpu();
sq->sqb_ptrs[sq->sqb_count++] = (u64)bufptr;
}
}
@@ -1381,21 +1377,18 @@ int otx2_rq_aura_pool_init(struct otx2_nic *pfvf)
if (err)
goto fail;

- get_cpu();
/* Allocate pointers and free them to aura/pool */
for (pool_id = 0; pool_id < hw->rqpool_cnt; pool_id++) {
pool = &pfvf->qset.pool[pool_id];
for (ptr = 0; ptr < num_ptrs; ptr++) {
err = otx2_alloc_rbuf(pfvf, pool, &bufptr);
if (err)
- goto err_mem;
+ return -ENOMEM;
pfvf->hw_ops->aura_freeptr(pfvf, pool_id,
bufptr + OTX2_HEAD_ROOM);
}
}
-err_mem:
- put_cpu();
- return err ? -ENOMEM : 0;
+ return 0;
fail:
otx2_mbox_reset(&pfvf->mbox.mbox, 0);
otx2_aura_pool_free(pfvf);
diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h
index 095e5de78c0b..e685628b9294 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h
@@ -605,8 +605,10 @@ static inline void cn10k_aura_freeptr(void *dev, int aura, u64 buf)
u64 ptrs[2];

ptrs[1] = buf;
+ get_cpu();
/* Free only one buffer at time during init and teardown */
__cn10k_aura_freeptr(pfvf, aura, ptrs, 2);
+ put_cpu();
}

/* Alloc pointer from pool/aura */
--
2.38.1