[PATCH 2/4] cifs: Fix in error types returned for out-of-credit situations.

[PATCH 2/4] cifs: Fix in error types returned for out-of-credit situations.

[Shyam Prasad N]

-- 
Regards,
Shyam

Re: [PATCH 2/4] cifs: Fix in error types returned for out-of-credit situations.

[Shyam Prasad N]

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On Thu, Feb 4, 2021 at 12:08 AM Shyam Prasad N <nspmangalore@gmail.com> wrote:
>
> --
> Regards,
> Shyam



-- 
Regards,
Shyam

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From 737b8d71d9cc3ef2b2484f246cec4b8135e576d4 Mon Sep 17 00:00:00 2001
From: Shyam Prasad N <sprasad@microsoft.com>
Date: Wed, 3 Feb 2021 22:58:38 -0800
Subject: [PATCH 2/4] cifs: Fix in error types returned for out-of-credit
 situations.

For failure by timeout waiting for credits, changed the error
returned to the app with EBUSY, instead of ENOTSUPP. This is done
because this situation is possible even in non-buggy cases. i.e.
overloaded server can return 0 credits until done with outstanding
requests. And this feels like a better error to return to the app.

For cases of zero credits found even when there are no requests
in flight, replaced ENOTSUPP with EDEADLK, since we're avoiding
deadlock here by returning error.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
---
 fs/cifs/transport.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 41223a9ee086..39e87705840d 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -567,7 +567,7 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 					server->hostname, num_credits, 0);
 				cifs_server_dbg(VFS, "wait timed out after %d ms\n",
 					 timeout);
-				return -ENOTSUPP;
+				return -EBUSY;
 			}
 			if (rc == -ERESTARTSYS)
 				return -ERESTARTSYS;
@@ -609,7 +609,7 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 						0);
 					cifs_server_dbg(VFS, "wait timed out after %d ms\n",
 						 timeout);
-					return -ENOTSUPP;
+					return -EBUSY;
 				}
 				if (rc == -ERESTARTSYS)
 					return -ERESTARTSYS;
@@ -687,7 +687,7 @@ wait_for_compound_request(struct TCP_Server_Info *server, int num,
 					server->hostname, scredits, sin_flight);
 			cifs_dbg(FYI, "%s: %d requests in flight, needed %d total=%d\n",
 					__func__, sin_flight, num, scredits);
-			return -ENOTSUPP;
+			return -EDEADLK;
 		}
 	}
 	spin_unlock(&server->req_lock);
-- 
2.25.1

Re: [PATCH 2/4] cifs: Fix in error types returned for out-of-credit situations.

[Aurélien Aptel]

Shyam Prasad N <nspmangalore@gmail.com> writes:
> For cases of zero credits found even when there are no requests
> in flight, replaced ENOTSUPP with EDEADLK, since we're avoiding
> deadlock here by returning error.

Seems ok. libc can have different behaviours depending on error but it
should be ok I think and better than ENOTSUPP.

Reviewed-by: Aurelien Aptel <aaptel@suse.com>

Cheers,
-- 
Aurélien Aptel / SUSE Labs Samba Team
GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)

Re: [PATCH 2/4] cifs: Fix in error types returned for out-of-credit situations.

[Steve French]

Is it safe enough to cc:stable?  Is it important enough to get this
fix in ASAP for 5.11-rc7 vs. 5.12?

On Thu, Feb 4, 2021 at 4:16 AM Aurélien Aptel <aaptel@suse.com> wrote:
>
> Shyam Prasad N <nspmangalore@gmail.com> writes:
> > For cases of zero credits found even when there are no requests
> > in flight, replaced ENOTSUPP with EDEADLK, since we're avoiding
> > deadlock here by returning error.
>
> Seems ok. libc can have different behaviours depending on error but it
> should be ok I think and better than ENOTSUPP.
>
> Reviewed-by: Aurelien Aptel <aaptel@suse.com>
>
> Cheers,
> --
> Aurélien Aptel / SUSE Labs Samba Team
> GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)
>


-- 
Thanks,

Steve

Re: [PATCH 2/4] cifs: Fix in error types returned for out-of-credit situations.

[Shyam Prasad N]

5.12 should be fine.

On Thu, Feb 4, 2021 at 8:49 AM Steve French <smfrench@gmail.com> wrote:
>
> Is it safe enough to cc:stable?  Is it important enough to get this
> fix in ASAP for 5.11-rc7 vs. 5.12?
>
> On Thu, Feb 4, 2021 at 4:16 AM Aurélien Aptel <aaptel@suse.com> wrote:
> >
> > Shyam Prasad N <nspmangalore@gmail.com> writes:
> > > For cases of zero credits found even when there are no requests
> > > in flight, replaced ENOTSUPP with EDEADLK, since we're avoiding
> > > deadlock here by returning error.
> >
> > Seems ok. libc can have different behaviours depending on error but it
> > should be ok I think and better than ENOTSUPP.
> >
> > Reviewed-by: Aurelien Aptel <aaptel@suse.com>
> >
> > Cheers,
> > --
> > Aurélien Aptel / SUSE Labs Samba Team
> > GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> > SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
> > GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)
> >
>
>
> --
> Thanks,
>
> Steve



-- 
Regards,
Shyam