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smb: client: fix cifs_pick_channel when channels are equally loaded

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cifs_pick_channel uses (start % chan_count) when channels are equally
loaded, but that can return a channel that failed the eligibility
checks.

Drop the fallback and return the scan-selected channel instead. If none
is eligible, keep the existing behavior of using the primary channel.

Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
Acked-by: Meetakshi Setiya <msetiya@microsoft.com>
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Henrique Carvalho
2026-02-21 01:59:44 -03:00
committed by Steve French
parent 6de23f81a5
commit 663c28469d
1 changed files with 10 additions and 11 deletions
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21
fs/smb/client/transport.c
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@@ -807,16 +807,21 @@ cifs_cancelled_callback(struct TCP_Server_Info *server, struct mid_q_entry *mid)
}
/*
* Return a channel (master if none) of @ses that can be used to send
* regular requests.
* cifs_pick_channel - pick an eligible channel for network operations
*
* If we are currently binding a new channel (negprot/sess.setup),
* return the new incomplete channel.
* @ses: session reference
*
* Select an eligible channel (not terminating and not marked as needing
* reconnect), preferring the least loaded one. If no eligible channel is
* found, fall back to the primary channel (index 0).
*
* Return: TCP_Server_Info pointer for the chosen channel, or NULL if @ses is
* NULL.
*/
struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
{
uint index = 0;
unsigned int min_in_flight = UINT_MAX, max_in_flight = 0;
unsigned int min_in_flight = UINT_MAX;
struct TCP_Server_Info *server = NULL;
int i, start, cur;
@@ -846,14 +851,8 @@ struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
min_in_flight = server->in_flight;
index = cur;
}
if (server->in_flight > max_in_flight)
max_in_flight = server->in_flight;
}
/* if all channels are equally loaded, fall back to round-robin */
if (min_in_flight == max_in_flight)
index = (uint)start % ses->chan_count;
server = ses->chans[index].server;
spin_unlock(&ses->chan_lock);