Re: [PATCH v8 10/16] lpfc: vmid: Functions to manage vmids

[Hannes Reinecke <hare@suse.de>]

On 3/4/21 6:27 AM, Muneendra wrote:
> From: Gaurav Srivastava <gaurav.srivastava@broadcom.com>
> 
> This patch contains the routines to save, retrieve and remove the vmids
> from the data structure. A hash table is used to save the vmids and
> the corresponding UUIDs associated with the application/VMs.
> 
> Signed-off-by: Gaurav Srivastava  <gaurav.srivastava@broadcom.com>
> Signed-off-by: James Smart <jsmart2021@gmail.com>
> 
> ---
> v8:
> Added correct return value and error codes
> 
> v7:
> No change
> 
> v6:
> Added Forward declarations and functions to static
> 
> v5:
> Changed Return code to non-numeric/Symbol
> 
> v4:
> No change
> 
> v3:
> No change
> 
> v2:
> Ported the patch on top of 5.10/scsi-queue
> ---
>   drivers/scsi/lpfc/lpfc_scsi.c | 148 ++++++++++++++++++++++++++++++++++
>   1 file changed, 148 insertions(+)
> 
> diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
> index e96e767faa2a..b71602878559 100644
> --- a/drivers/scsi/lpfc/lpfc_scsi.c
> +++ b/drivers/scsi/lpfc/lpfc_scsi.c
> @@ -28,6 +28,7 @@
>   #include <asm/unaligned.h>
>   #include <linux/t10-pi.h>
>   #include <linux/crc-t10dif.h>
> +#include <linux/blk-cgroup.h>
>   #include <net/checksum.h>
>   
>   #include <scsi/scsi.h>
> @@ -86,6 +87,14 @@ static void
>   lpfc_release_scsi_buf_s3(struct lpfc_hba *phba, struct lpfc_io_buf *psb);
>   static int
>   lpfc_prot_group_type(struct lpfc_hba *phba, struct scsi_cmnd *sc);
> +static int
> +lpfc_put_vmid_in_hashtable(struct lpfc_vport *vport, u32 hash,
> +			   struct lpfc_vmid *vmp);
> +static void lpfc_vmid_update_entry(struct lpfc_vport *vport, struct scsi_cmnd
> +				   *cmd, struct lpfc_vmid *vmp,
> +				   union lpfc_vmid_io_tag *tag);
> +static void lpfc_vmid_assign_cs_ctl(struct lpfc_vport *vport,
> +				    struct lpfc_vmid *vmid);
>   
>   static inline unsigned
>   lpfc_cmd_blksize(struct scsi_cmnd *sc)
> @@ -5131,6 +5140,145 @@ void lpfc_poll_timeout(struct timer_list *t)
>   	}
>   }
>   
> +/*
> + * lpfc_get_vmid_from_hastable - search the UUID in the hash table

Should be 'lpfc_get_vmid_from_hashtable()'.

> + * @vport: The virtual port for which this call is being executed.
> + * @hash: calculated hash value
> + * @buf: uuid associated with the VE
> + * Returns the vmid entry associated with the UUID
> + * Make sure to acquire the appropriate lock before invoking this routine.
> + */
> +struct lpfc_vmid *lpfc_get_vmid_from_hastable(struct lpfc_vport *vport,
> +					      u32 hash, u8 *buf)
> +{
> +	struct lpfc_vmid *vmp;
> +	u16 count = 0;
> +
> +	while (count < LPFC_VMID_HASH_SIZE) {
> +		vmp = vport->hash_table[hash];
> +		if (vmp) {
> +			if (strncmp(&vmp->host_vmid[0], buf, 16) == 0)
> +				return vmp;
> +		} else {
> +			return NULL;
> +		}
> +		/* search the next available slot and continue till entry */
> +		/* is found */
> +		count++;
> +		hash++;
> +
> +		/* or the end is reached */
> +		if (hash == LPFC_VMID_HASH_SIZE)
> +			hash = 0;
> +	}
> +	return NULL;
> +}
> +
> +/*
> + * lpfc_put_vmid_from_hastable - put the VMID in the hash table
> + * @vport: The virtual port for which this call is being executed.
> + * @hash - calculated hash value
> + * @vmp: Pointer to a VMID entry representing a VM sending IO
> + *
> + * This routine will insert the newly acquired vmid entity in the hash table.
> + * Make sure to acquire the appropriate lock before invoking this routine.
> + */
> +static int
> +lpfc_put_vmid_in_hashtable(struct lpfc_vport *vport, u32 hash,
> +			   struct lpfc_vmid *vmp)
> +{
> +	int count = 0;
> +
> +	while (count < LPFC_VMID_HASH_SIZE) {
> +		if (!vport->hash_table[hash]) {
> +			vport->hash_table[hash] = vmp;
> +			vmp->hash_index = hash;
> +			return 0;
> +		}
> +		/* if the slot is already occupied, a collision has occurred. */
> +		/* Store in the next available slot */
> +		count++;
> +		hash++;
> +		/* table is full */
> +		if (hash == LPFC_VMID_HASH_SIZE)
> +			hash = 0;
> +	}
> +	return -ENOMEM;
> +}
> +
> +/*
> + * lpfc_vmid_hash_fn - creates a hash value of the UUID
> + * @vmid: uuid associated with the VE
> + * @len: length of the vmid string
> + * Returns the calculated hash value
> + */
> +int lpfc_vmid_hash_fn(const char *vmid, int len)
> +{
> +	int c;
> +	int hash = 0;
> +
> +	if (len == 0)
> +		return 0;
> +	while (len--) {
> +		c = *vmid++;
> +		if (c >= 'A' && c <= 'Z')
> +			c += 'a' - 'A';
> +
> +		hash = (hash + (c << LPFC_VMID_HASH_SHIFT) +
> +			(c >> LPFC_VMID_HASH_SHIFT)) * 19;
> +	}
> +
> +	return hash & LPFC_VMID_HASH_MASK;
> +}
> +

Any particular reason why you didn't use a generic hashtable 
implementation here?
(cf include/linux/hashtable.h)

> +/*
> + * lpfc_vmid_update_entry - update the vmid entry in the hash table
> + * @vport: The virtual port for which this call is being executed.
> + * @cmd: address of scsi cmmd descriptor
> + * @vmp: Pointer to a VMID entry representing a VM sending IO
> + * @tag: VMID tag
> + */
> +static void lpfc_vmid_update_entry(struct lpfc_vport *vport, struct scsi_cmnd
> +				   *cmd, struct lpfc_vmid *vmp,
> +				   union lpfc_vmid_io_tag *tag)
> +{
> +	u64 *lta;
> +
> +	if (vport->vmid_priority_tagging)
> +		tag->cs_ctl_vmid = vmp->un.cs_ctl_vmid;
> +	else
> +		tag->app_id = vmp->un.app_id;
> +
> +	if (cmd->sc_data_direction == DMA_TO_DEVICE)
> +		vmp->io_wr_cnt++;
> +	else
> +		vmp->io_rd_cnt++;
> +
> +	/* update the last access timestamp in the table */
> +	lta = per_cpu_ptr(vmp->last_io_time, raw_smp_processor_id());
> +	*lta = jiffies;
> +}
> +
> +static void lpfc_vmid_assign_cs_ctl(struct lpfc_vport *vport,
> +				    struct lpfc_vmid *vmid)
> +{
> +	u32 hash;
> +	struct lpfc_vmid *pvmid;
> +
> +	if (vport->port_type == LPFC_PHYSICAL_PORT) {
> +		vmid->un.cs_ctl_vmid = lpfc_vmid_get_cs_ctl(vport);
> +	} else {
> +		hash = lpfc_vmid_hash_fn(vmid->host_vmid, vmid->vmid_len);
> +		pvmid =
> +		    lpfc_get_vmid_from_hastable(vport->phba->pport, hash,
> +						vmid->host_vmid);
> +		if (pvmid)
> +			vmid->un.cs_ctl_vmid = pvmid->un.cs_ctl_vmid;
> +		else
> +			vmid->un.cs_ctl_vmid = lpfc_vmid_get_cs_ctl(vport);
> +	}
> +}
> +
>   /**
>    * lpfc_queuecommand - scsi_host_template queuecommand entry point
>    * @shost: kernel scsi host pointer.
> 
Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer

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