octeontx2-pf: Fix the use of GFP_KERNEL in atomic context on rt

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2040643

commit 55ba18d
Author: Kevin Hao <haokexin@gmail.com>
Date:   Wed Jan 18 15:13:00 2023 +0800

    octeontx2-pf: Fix the use of GFP_KERNEL in atomic context on rt

    The commit 4af1b64 ("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 87b93b6
    ("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 87b93b6 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: 4af1b64 ("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>

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>

Author: michich

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c

@@ -1012,7 +1012,6 @@ 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
@@ -1032,7 +1031,6 @@ 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;
 }
 
@@ -1387,9 +1385,7 @@ 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;
 		}
 	}
@@ -1435,21 +1431,18 @@ 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);

drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h

@@ -660,8 +660,10 @@ 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 */