linux-sg2042/drivers/scsi/cxlflash/common.h

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/*
* CXL Flash Device Driver
*
* Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
* Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
*
* Copyright (C) 2015 IBM Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _CXLFLASH_COMMON_H
#define _CXLFLASH_COMMON_H
#include <linux/list.h>
#include <linux/rwsem.h>
#include <linux/types.h>
#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
cxlflash: Fix to avoid corrupting adapter fops The fops owned by the adapter can be corrupted in certain scenarios, opening a window where certain fops are temporarily NULLed before being reset to their proper value. This can potentially lead software to make incorrect decisions, leaving the user with the inability to function as intended. An example of this behavior can be observed when there are a number of users with a high rate of turn around (attach to LUN, perform an I/O, detach from LUN, repeat). Every so often a user is given a valid context and adapter file descriptor, but the file associated with the descriptor lacks the correct read permission bit (FMODE_CAN_READ) and thus the read system call bails before calling the valid read fop. Background: The fops is stored in the adapter structure to provide the ability to lookup the adapter structure from within the fop handler. CXL services use the file's private_data and at present, the CXL context does not have a private section. In an effort to limit areas of the cxlflash driver with code specific the superpipe function, a design choice was made to keep the details of the fops situated away from the legacy portions of the driver. This drove the behavior that the adapter fops is set at the beginning of the disk attach ioctl handler when there are no users present. The corruption that this fix remedies is due to the fact that the fops is initially defaulted to values found within a static structure. When the fops is handed down to the CXL services later in the attach path, certain services are patched. The fops structure remains correct until the user count drops to 0 and the fops is reset, triggering the process to repeat again. The user counts are tightly coupled with the creation and deletion of the user context. If multiple users perform a disk attach at the same time, when the user count is currently 0, some users can be in the middle of obtaining a file descriptor and have not yet reached the context creation code that [in addition to creating the context] increments the user count. Subsequent users coming in to perform the attach see that the user count is still 0, and reinitialize the fops, temporarily removing the patched fops. The users that are in the middle obtaining their file descriptor may then receive an invalid descriptor. The fix simply removes the user count altogether and moves the fops initialization to probe time such that it is only performed one time for the life of the adapter. In the future, if the CXL services adopt a private member for their context, that could be used to store the adapter structure reference and cxlflash could revert to a model that does not require an embedded fops. Signed-off-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com> Signed-off-by: Manoj N. Kumar <manoj@linux.vnet.ibm.com> Reviewed-by: Brian King <brking@linux.vnet.ibm.com> Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> Reviewed-by: Daniel Axtens <dja@axtens.net> Reviewed-by: Tomas Henzl <thenzl@redhat.com> Signed-off-by: James Bottomley <JBottomley@Odin.com>
2015-10-22 04:15:37 +08:00
extern const struct file_operations cxlflash_cxl_fops;
#define MAX_CONTEXT CXLFLASH_MAX_CONTEXT /* num contexts per afu */
#define CXLFLASH_BLOCK_SIZE 4096 /* 4K blocks */
#define CXLFLASH_MAX_XFER_SIZE 16777216 /* 16MB transfer */
#define CXLFLASH_MAX_SECTORS (CXLFLASH_MAX_XFER_SIZE/512) /* SCSI wants
max_sectors
in units of
512 byte
sectors
*/
#define NUM_RRQ_ENTRY 16 /* for master issued cmds */
#define MAX_RHT_PER_CONTEXT (PAGE_SIZE / sizeof(struct sisl_rht_entry))
/* AFU command retry limit */
#define MC_RETRY_CNT 5 /* sufficient for SCSI check and
certain AFU errors */
/* Command management definitions */
#define CXLFLASH_NUM_CMDS (2 * CXLFLASH_MAX_CMDS) /* Must be a pow2 for
alignment and more
efficient array
index derivation
*/
#define CXLFLASH_MAX_CMDS 16
#define CXLFLASH_MAX_CMDS_PER_LUN CXLFLASH_MAX_CMDS
static inline void check_sizes(void)
{
BUILD_BUG_ON_NOT_POWER_OF_2(CXLFLASH_NUM_CMDS);
}
/* AFU defines a fixed size of 4K for command buffers (borrow 4K page define) */
#define CMD_BUFSIZE SIZE_4K
/* flags in IOA status area for host use */
#define B_DONE 0x01
#define B_ERROR 0x02 /* set with B_DONE */
#define B_TIMEOUT 0x04 /* set with B_DONE & B_ERROR */
enum cxlflash_lr_state {
LINK_RESET_INVALID,
LINK_RESET_REQUIRED,
LINK_RESET_COMPLETE
};
enum cxlflash_init_state {
INIT_STATE_NONE,
INIT_STATE_PCI,
INIT_STATE_AFU,
INIT_STATE_SCSI
};
enum cxlflash_state {
STATE_NORMAL, /* Normal running state, everything good */
STATE_RESET, /* Reset state, trying to reset/recover */
STATE_FAILTERM /* Failed/terminating state, error out users/threads */
};
/*
* Each context has its own set of resource handles that is visible
* only from that context.
*/
struct cxlflash_cfg {
struct afu *afu;
struct cxl_context *mcctx;
struct pci_dev *dev;
struct pci_device_id *dev_id;
struct Scsi_Host *host;
ulong cxlflash_regs_pci;
struct work_struct work_q;
enum cxlflash_init_state init_state;
enum cxlflash_lr_state lr_state;
int lr_port;
atomic_t scan_host_needed;
struct cxl_afu *cxl_afu;
struct pci_dev *parent_dev;
atomic_t recovery_threads;
struct mutex ctx_recovery_mutex;
struct mutex ctx_tbl_list_mutex;
struct rw_semaphore ioctl_rwsem;
struct ctx_info *ctx_tbl[MAX_CONTEXT];
struct list_head ctx_err_recovery; /* contexts w/ recovery pending */
struct file_operations cxl_fops;
/* Parameters that are LUN table related */
int last_lun_index[CXLFLASH_NUM_FC_PORTS];
int promote_lun_index;
struct list_head lluns; /* list of llun_info structs */
wait_queue_head_t tmf_waitq;
spinlock_t tmf_slock;
bool tmf_active;
wait_queue_head_t reset_waitq;
enum cxlflash_state state;
};
struct afu_cmd {
struct sisl_ioarcb rcb; /* IOARCB (cache line aligned) */
struct sisl_ioasa sa; /* IOASA must follow IOARCB */
spinlock_t slock;
struct completion cevent;
char *buf; /* per command buffer */
struct afu *parent;
int slot;
atomic_t free;
u8 cmd_tmf:1;
/* As per the SISLITE spec the IOARCB EA has to be 16-byte aligned.
* However for performance reasons the IOARCB/IOASA should be
* cache line aligned.
*/
} __aligned(cache_line_size());
struct afu {
/* Stuff requiring alignment go first. */
u64 rrq_entry[NUM_RRQ_ENTRY]; /* 128B RRQ */
/*
* Command & data for AFU commands.
*/
struct afu_cmd cmd[CXLFLASH_NUM_CMDS];
/* Beware of alignment till here. Preferably introduce new
* fields after this point
*/
/* AFU HW */
struct cxl_ioctl_start_work work;
struct cxlflash_afu_map __iomem *afu_map; /* entire MMIO map */
struct sisl_host_map __iomem *host_map; /* MC host map */
struct sisl_ctrl_map __iomem *ctrl_map; /* MC control map */
struct kref mapcount;
ctx_hndl_t ctx_hndl; /* master's context handle */
u64 *hrrq_start;
u64 *hrrq_end;
u64 *hrrq_curr;
bool toggle;
bool read_room;
atomic64_t room;
u64 hb;
u32 cmd_couts; /* Number of command checkouts */
u32 internal_lun; /* User-desired LUN mode for this AFU */
char version[16];
u64 interface_version;
struct cxlflash_cfg *parent; /* Pointer back to parent cxlflash_cfg */
};
static inline u64 lun_to_lunid(u64 lun)
{
__be64 lun_id;
int_to_scsilun(lun, (struct scsi_lun *)&lun_id);
return be64_to_cpu(lun_id);
}
int cxlflash_afu_sync(struct afu *, ctx_hndl_t, res_hndl_t, u8);
void cxlflash_list_init(void);
void cxlflash_term_global_luns(void);
void cxlflash_free_errpage(void);
int cxlflash_ioctl(struct scsi_device *, int, void __user *);
void cxlflash_stop_term_user_contexts(struct cxlflash_cfg *);
int cxlflash_mark_contexts_error(struct cxlflash_cfg *);
void cxlflash_term_local_luns(struct cxlflash_cfg *);
void cxlflash_restore_luntable(struct cxlflash_cfg *);
#endif /* ifndef _CXLFLASH_COMMON_H */