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scsi: core: Introduce a new list for SCSI proc directory entries

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Instead of using scsi_host_template members to track the SCSI proc
directory entries, track these entries in a list. This changes the time
needed for looking up the proc dir pointer from O(1) into O(n). This is
considered acceptable since the number of SCSI host adapter types per host
is usually small (less than ten).

This change has been tested by attaching two USB storage devices to a qemu
host:

$ grep -aH . /proc/scsi/usb-storage/*
/proc/scsi/usb-storage/7:   Host scsi7: usb-storage
/proc/scsi/usb-storage/7:       Vendor: QEMU
/proc/scsi/usb-storage/7:      Product: QEMU USB HARDDRIVE
/proc/scsi/usb-storage/7:Serial Number: 1-0000:00:02.1:00.0-6
/proc/scsi/usb-storage/7:     Protocol: Transparent SCSI
/proc/scsi/usb-storage/7:    Transport: Bulk
/proc/scsi/usb-storage/7:       Quirks: SANE_SENSE
/proc/scsi/usb-storage/8:   Host scsi8: usb-storage
/proc/scsi/usb-storage/8:       Vendor: QEMU
/proc/scsi/usb-storage/8:      Product: QEMU USB HARDDRIVE
/proc/scsi/usb-storage/8:Serial Number: 1-0000:00:02.1:00.0-7
/proc/scsi/usb-storage/8:     Protocol: Transparent SCSI
/proc/scsi/usb-storage/8:    Transport: Bulk
/proc/scsi/usb-storage/8:       Quirks: SANE_SENSE

This commit prepares for constifying most SCSI host templates.

Reviewed-by: John Garry <john.garry@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20221015002418.30955-5-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche 2022-10-14 17:24:14 -07:00 committed by Martin K. Petersen
parent ecca3f9b16
commit 036abd6140
3 changed files with 102 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/scsi/scsi_priv.h
View File

@ -111,8 +111,8 @@ extern void scsi_evt_thread(struct work_struct *work);
/* scsi_proc.c */ /* scsi_proc.c */
#ifdef CONFIG_SCSI_PROC_FS #ifdef CONFIG_SCSI_PROC_FS
extern int scsi_proc_hostdir_add(struct scsi_host_template *); extern int scsi_proc_hostdir_add(const struct scsi_host_template *);
extern void scsi_proc_hostdir_rm(struct scsi_host_template *); extern void scsi_proc_hostdir_rm(const struct scsi_host_template *);
extern void scsi_proc_host_add(struct Scsi_Host *); extern void scsi_proc_host_add(struct Scsi_Host *);
extern void scsi_proc_host_rm(struct Scsi_Host *); extern void scsi_proc_host_rm(struct Scsi_Host *);
extern int scsi_init_procfs(void); extern int scsi_init_procfs(void);

121
drivers/scsi/scsi_proc.c
View File

@ -43,8 +43,23 @@
static struct proc_dir_entry *proc_scsi; static struct proc_dir_entry *proc_scsi;
/* Protect sht->present and sht->proc_dir */ /* Protects scsi_proc_list */
static DEFINE_MUTEX(global_host_template_mutex); static DEFINE_MUTEX(global_host_template_mutex);
static LIST_HEAD(scsi_proc_list);
/**
* struct scsi_proc_entry - (host template, SCSI proc dir) association
* @entry: entry in scsi_proc_list.
* @sht: SCSI host template associated with the procfs directory.
* @proc_dir: procfs directory associated with the SCSI host template.
* @present: Number of SCSI hosts instantiated for @sht.
*/
struct scsi_proc_entry {
struct list_head entry;
const struct scsi_host_template *sht;
struct proc_dir_entry *proc_dir;
unsigned int present;
};
static ssize_t proc_scsi_host_write(struct file *file, const char __user *buf, static ssize_t proc_scsi_host_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos) size_t count, loff_t *ppos)
@ -83,6 +98,32 @@ static int proc_scsi_host_open(struct inode *inode, struct file *file)
4 * PAGE_SIZE); 4 * PAGE_SIZE);
} }
static struct scsi_proc_entry *
__scsi_lookup_proc_entry(const struct scsi_host_template *sht)
{
struct scsi_proc_entry *e;
lockdep_assert_held(&global_host_template_mutex);
list_for_each_entry(e, &scsi_proc_list, entry)
if (e->sht == sht)
return e;
return NULL;
}
static struct scsi_proc_entry *
scsi_lookup_proc_entry(const struct scsi_host_template *sht)
{
struct scsi_proc_entry *e;
mutex_lock(&global_host_template_mutex);
e = __scsi_lookup_proc_entry(sht);
mutex_unlock(&global_host_template_mutex);
return e;
}
/** /**
* scsi_template_proc_dir() - returns the procfs dir for a SCSI host template * scsi_template_proc_dir() - returns the procfs dir for a SCSI host template
* @sht: SCSI host template pointer. * @sht: SCSI host template pointer.
@ -90,7 +131,9 @@ static int proc_scsi_host_open(struct inode *inode, struct file *file)
struct proc_dir_entry * struct proc_dir_entry *
scsi_template_proc_dir(const struct scsi_host_template *sht) scsi_template_proc_dir(const struct scsi_host_template *sht)
{ {
return sht->proc_dir; struct scsi_proc_entry *e = scsi_lookup_proc_entry(sht);
return e ? e->proc_dir : NULL;
} }
EXPORT_SYMBOL_GPL(scsi_template_proc_dir); EXPORT_SYMBOL_GPL(scsi_template_proc_dir);
@ -108,24 +151,41 @@ static const struct proc_ops proc_scsi_ops = {
* *
* Sets sht->proc_dir to the new directory. * Sets sht->proc_dir to the new directory.
*/ */
int scsi_proc_hostdir_add(struct scsi_host_template *sht) int scsi_proc_hostdir_add(const struct scsi_host_template *sht)
{ {
int ret = 0; struct scsi_proc_entry *e;
int ret;
if (!sht->show_info) if (!sht->show_info)
return 0; return 0;
mutex_lock(&global_host_template_mutex); mutex_lock(&global_host_template_mutex);
if (!sht->present++) { e = __scsi_lookup_proc_entry(sht);
sht->proc_dir = proc_mkdir(sht->proc_name, proc_scsi); if (!e) {
if (!sht->proc_dir) { e = kzalloc(sizeof(*e), GFP_KERNEL);
printk(KERN_ERR "%s: proc_mkdir failed for %s\n", if (!e) {
__func__, sht->proc_name);
ret = -ENOMEM; ret = -ENOMEM;
goto unlock;
} }
} }
if (e->present++)
goto success;
e->proc_dir = proc_mkdir(sht->proc_name, proc_scsi);
if (!e->proc_dir) {
printk(KERN_ERR "%s: proc_mkdir failed for %s\n", __func__,
sht->proc_name);
ret = -ENOMEM;
goto unlock;
}
e->sht = sht;
list_add_tail(&e->entry, &scsi_proc_list);
success:
e = NULL;
ret = 0;
unlock:
mutex_unlock(&global_host_template_mutex); mutex_unlock(&global_host_template_mutex);
kfree(e);
return ret; return ret;
} }
@ -133,15 +193,19 @@ int scsi_proc_hostdir_add(struct scsi_host_template *sht)
* scsi_proc_hostdir_rm - remove directory in /proc for a scsi host * scsi_proc_hostdir_rm - remove directory in /proc for a scsi host
* @sht: owner of directory * @sht: owner of directory
*/ */
void scsi_proc_hostdir_rm(struct scsi_host_template *sht) void scsi_proc_hostdir_rm(const struct scsi_host_template *sht)
{ {
struct scsi_proc_entry *e;
if (!sht->show_info) if (!sht->show_info)
return; return;
mutex_lock(&global_host_template_mutex); mutex_lock(&global_host_template_mutex);
if (!--sht->present && sht->proc_dir) { e = __scsi_lookup_proc_entry(sht);
if (e && !--e->present) {
remove_proc_entry(sht->proc_name, proc_scsi); remove_proc_entry(sht->proc_name, proc_scsi);
sht->proc_dir = NULL; list_del(&e->entry);
kfree(e);
} }
mutex_unlock(&global_host_template_mutex); mutex_unlock(&global_host_template_mutex);
} }
@ -153,20 +217,29 @@ void scsi_proc_hostdir_rm(struct scsi_host_template *sht)
*/ */
void scsi_proc_host_add(struct Scsi_Host *shost) void scsi_proc_host_add(struct Scsi_Host *shost)
{ {
struct scsi_host_template *sht = shost->hostt; const struct scsi_host_template *sht = shost->hostt;
struct scsi_proc_entry *e;
struct proc_dir_entry *p; struct proc_dir_entry *p;
char name[10]; char name[10];
if (!sht->proc_dir) if (!sht->show_info)
return; return;
e = scsi_lookup_proc_entry(sht);
if (!e)
goto err;
sprintf(name,"%d", shost->host_no); sprintf(name,"%d", shost->host_no);
p = proc_create_data(name, S_IRUGO | S_IWUSR, p = proc_create_data(name, S_IRUGO | S_IWUSR, e->proc_dir,
sht->proc_dir, &proc_scsi_ops, shost); &proc_scsi_ops, shost);
if (!p) if (!p)
printk(KERN_ERR "%s: Failed to register host %d in" goto err;
"%s\n", __func__, shost->host_no, return;
sht->proc_name);
err:
shost_printk(KERN_ERR, shost,
"%s: Failed to register host (%s failed)\n", __func__,
e ? "proc_create_data()" : "scsi_proc_hostdir_add()");
} }
/** /**
@ -175,13 +248,19 @@ void scsi_proc_host_add(struct Scsi_Host *shost)
*/ */
void scsi_proc_host_rm(struct Scsi_Host *shost) void scsi_proc_host_rm(struct Scsi_Host *shost)
{ {
const struct scsi_host_template *sht = shost->hostt;
struct scsi_proc_entry *e;
char name[10]; char name[10];
if (!shost->hostt->proc_dir) if (!sht->show_info)
return;
e = scsi_lookup_proc_entry(sht);
if (!e)
return; return;
sprintf(name,"%d", shost->host_no); sprintf(name,"%d", shost->host_no);
remove_proc_entry(name, shost->hostt->proc_dir); remove_proc_entry(name, e->proc_dir);
} }
/** /**
* proc_print_scsidevice - return data about this host * proc_print_scsidevice - return data about this host

12
include/scsi/scsi_host.h
View File

@ -357,12 +357,6 @@ struct scsi_host_template {
*/ */
const char *proc_name; const char *proc_name;
/*
* Used to store the procfs directory if a driver implements the
* show_info method.
*/
struct proc_dir_entry *proc_dir;
/* /*
* This determines if we will use a non-interrupt driven * This determines if we will use a non-interrupt driven
* or an interrupt driven scheme. It is set to the maximum number * or an interrupt driven scheme. It is set to the maximum number
@ -423,12 +417,6 @@ struct scsi_host_template {
*/ */
short cmd_per_lun; short cmd_per_lun;
/*
* present contains counter indicating how many boards of this
* type were found when we did the scan.
*/
unsigned char present;
/* If use block layer to manage tags, this is tag allocation policy */ /* If use block layer to manage tags, this is tag allocation policy */
int tag_alloc_policy; int tag_alloc_policy;