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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>
Linux kernel
============
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.