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SubjectRe: [net PATCH] octeontx2-pf: Use GFP_ATOMIC in atomic context
On Tue, Jan 10, 2023 at 8:54 AM Geethasowjanya Akula <gakula@marvell.com> wrote:
>
>
>
> -----Original Message-----
> From: Leon Romanovsky <leon@kernel.org>
> Sent: Sunday, January 8, 2023 6:39 PM
> To: Geethasowjanya Akula <gakula@marvell.com>
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; kuba@kernel.org; pabeni@redhat.com; davem@davemloft.net; edumazet@google.com; Subbaraya Sundeep Bhatta <sbhatta@marvell.com>; Hariprasad Kelam <hkelam@marvell.com>; Sunil Kovvuri Goutham <sgoutham@marvell.com>
> Subject: [EXT] Re: [net PATCH] octeontx2-pf: Use GFP_ATOMIC in atomic context
>
> External Email
>
> ----------------------------------------------------------------------
> On Sat, Jan 07, 2023 at 10:11:39AM +0530, Geetha sowjanya wrote:
> >> Use GFP_ATOMIC flag instead of GFP_KERNEL while allocating memory in
> >> atomic context.
>
> >Awesome, but the changed functions don't run in atomic context.
>
> drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
> 1368 /* Flush accumulated messages */
> 1369 err = otx2_sync_mbox_msg(&pfvf->mbox);
> 1370 if (err)
> 1371 goto fail;
> 1372
> 1373 get_cpu();
> ^^^^^^^^^
> The get_cpu() disables preemption.

Forcing GFP_ATOMIC in init functions is not desirable.

Please move around the get_cpu() so that we keep GFP_KERNEL whenever possible.

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
index 88f8772a61cd527c2ab138fb5a996470a7dfd456..2e628e12cd1ff92756f054639abd777ea185680f
100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
@@ -1370,7 +1370,6 @@ int otx2_sq_aura_pool_init(struct otx2_nic *pfvf)
if (err)
goto fail;

- get_cpu();
/* Allocate pointers and free them to aura/pool */
for (qidx = 0; qidx < hw->tot_tx_queues; qidx++) {
pool_id = otx2_get_pool_idx(pfvf, AURA_NIX_SQ, qidx);
@@ -1388,13 +1387,17 @@ int otx2_sq_aura_pool_init(struct otx2_nic *pfvf)
err = otx2_alloc_rbuf(pfvf, pool, &bufptr);
if (err)
goto err_mem;
+ /* __cn10k_aura_freeptr() needs to be called
+ * with preemption disabled.
+ */
+ get_cpu();
pfvf->hw_ops->aura_freeptr(pfvf, pool_id, bufptr);
+ put_cpu();
sq->sqb_ptrs[sq->sqb_count++] = (u64)bufptr;
}
}

err_mem:
- put_cpu();
return err ? -ENOMEM : 0;

fail:
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