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76631ffa2f
Previously the clients_lock was protecting the clients array against
concurrent addition/removal of clients but was also accessed from IRQ
context. This meant that it had to be a spinlock and that the add() and
remove() callbacks in which clients need to do allocation and take
mutexes can't be called under the clients_lock. To work around this these
callbacks were moved to workqueues. This not only introduced significant
complexity but is also subtly broken in at least one way.
In ism_dev_init() and ism_dev_exit() clients[i]->tgt_ism is used to
communicate the added/removed ISM device to the work function. While
write access to client[i]->tgt_ism is protected by the clients_lock and
the code waits that there is no pending add/remove work before and after
setting clients[i]->tgt_ism this is not enough. The problem is that the
wait happens based on per ISM device counters. Thus a concurrent
ism_dev_init()/ism_dev_exit() for a different ISM device may overwrite
a clients[i]->tgt_ism between unlocking the clients_lock and the
subsequent wait for the work to finnish.
Thankfully with the clients_lock no longer held in IRQ context it can be
turned into a mutex which can be held during the calls to add()/remove()
completely removing the need for the workqueues and the associated
broken housekeeping including the per ISM device counters and the
clients[i]->tgt_ism.
Fixes: 89e7d2ba61b7 ("net/ism: Add new API for client registration")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
94 lines
2.2 KiB
C
94 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Internal Shared Memory
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*
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* Definitions for the ISM module
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*
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* Copyright IBM Corp. 2022
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*/
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#ifndef _ISM_H
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#define _ISM_H
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#include <linux/workqueue.h>
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struct ism_dmb {
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u64 dmb_tok;
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u64 rgid;
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u32 dmb_len;
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u32 sba_idx;
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u32 vlan_valid;
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u32 vlan_id;
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void *cpu_addr;
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dma_addr_t dma_addr;
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};
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/* Unless we gain unexpected popularity, this limit should hold for a while */
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#define MAX_CLIENTS 8
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#define ISM_NR_DMBS 1920
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struct ism_dev {
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spinlock_t lock; /* protects the ism device */
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struct list_head list;
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struct pci_dev *pdev;
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struct ism_sba *sba;
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dma_addr_t sba_dma_addr;
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DECLARE_BITMAP(sba_bitmap, ISM_NR_DMBS);
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u8 *sba_client_arr; /* entries are indices into 'clients' array */
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void *priv[MAX_CLIENTS];
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struct ism_eq *ieq;
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dma_addr_t ieq_dma_addr;
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struct device dev;
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u64 local_gid;
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int ieq_idx;
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struct ism_client *subs[MAX_CLIENTS];
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};
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struct ism_event {
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u32 type;
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u32 code;
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u64 tok;
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u64 time;
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u64 info;
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};
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struct ism_client {
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const char *name;
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void (*add)(struct ism_dev *dev);
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void (*remove)(struct ism_dev *dev);
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void (*handle_event)(struct ism_dev *dev, struct ism_event *event);
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/* Parameter dmbemask contains a bit vector with updated DMBEs, if sent
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* via ism_move_data(). Callback function must handle all active bits
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* indicated by dmbemask.
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*/
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void (*handle_irq)(struct ism_dev *dev, unsigned int bit, u16 dmbemask);
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/* Private area - don't touch! */
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u8 id;
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};
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int ism_register_client(struct ism_client *client);
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int ism_unregister_client(struct ism_client *client);
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static inline void *ism_get_priv(struct ism_dev *dev,
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struct ism_client *client) {
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return dev->priv[client->id];
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}
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static inline void ism_set_priv(struct ism_dev *dev, struct ism_client *client,
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void *priv) {
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dev->priv[client->id] = priv;
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}
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int ism_register_dmb(struct ism_dev *dev, struct ism_dmb *dmb,
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struct ism_client *client);
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int ism_unregister_dmb(struct ism_dev *dev, struct ism_dmb *dmb);
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int ism_move(struct ism_dev *dev, u64 dmb_tok, unsigned int idx, bool sf,
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unsigned int offset, void *data, unsigned int size);
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u8 *ism_get_seid(void);
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const struct smcd_ops *ism_get_smcd_ops(void);
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#endif /* _ISM_H */
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