Re: [PATCH v3] misc: fastrpc: Add support for multiple PD from one process

[Ekansh Gupta <quic_ekangupt@quicinc.com>]

On 8/19/2024 4:35 PM, Caleb Connolly wrote:
> Hi Ekansh,
>
> On 08/08/2024 12:42, Ekansh Gupta wrote:
>> Memory intensive applications(which requires more tha 4GB) that wants
>> to offload tasks to DSP might have to split the tasks to multiple
>> user PD to make the resources available.
>>
>> For every call to DSP, fastrpc driver passes the process tgid which
>> works as an identifier for the DSP to enqueue the tasks to specific PD.
>> With current design, if any process opens device node more than once
>> and makes PD init request, same tgid will be passed to DSP which will
>> be considered a bad request and this will result in failure as the same
>> identifier cannot be used for multiple DSP PD.
>>
>> Assign and pass a client ID to DSP which would be assigned during device
>> open and will be dependent on the index of session allocated for the PD.
>> This will allow the same process to open the device more than once and
>> spawn multiple dynamic PD for ease of processing.
>
> A test tool to validate this fix and prevent it regressing in the future would be a good addition here.
Thanks for reviewing the change, Caleb.

This is more of a feature than a bug fix as it just adding support to spawn multiple user PDs from
single process. Test cases for this feature was added to the recent versions of Hexagon SDK.

--Ekansh
>>
>> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com>
>> ---
>> Changes in v2:
>>    - Reformatted commit text.
>>    - Moved from ida to idr.
>>    - Changed dsp_pgid data type.
>>    - Resolved memory leak.
>> Changes in v3:
>>    - Modified commit text.
>>    - Removed idr implementation.
>>    - Using session index for client id.
>>
>>   drivers/misc/fastrpc.c | 30 ++++++++++++++++--------------
>>   1 file changed, 16 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
>> index a7a2bcedb37e..0ce1eedcb2c3 100644
>> --- a/drivers/misc/fastrpc.c
>> +++ b/drivers/misc/fastrpc.c
>> @@ -38,6 +38,7 @@
>>   #define FASTRPC_INIT_HANDLE    1
>>   #define FASTRPC_DSP_UTILITIES_HANDLE    2
>>   #define FASTRPC_CTXID_MASK (0xFF0)
>> +#define FASTRPC_CLIENTID_MASK (16)
>>   #define INIT_FILELEN_MAX (2 * 1024 * 1024)
>>   #define INIT_FILE_NAMELEN_MAX (128)
>>   #define FASTRPC_DEVICE_NAME    "fastrpc"
>> @@ -298,7 +299,7 @@ struct fastrpc_user {
>>       struct fastrpc_session_ctx *sctx;
>>       struct fastrpc_buf *init_mem;
>>   -    int tgid;
>> +    int client_id;
>>       int pd;
>>       bool is_secure_dev;
>>       /* Lock for lists */
>> @@ -613,7 +614,7 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
>>       ctx->sc = sc;
>>       ctx->retval = -1;
>>       ctx->pid = current->pid;
>> -    ctx->tgid = user->tgid;
>> +    ctx->tgid = user->client_id;
>>       ctx->cctx = cctx;
>>       init_completion(&ctx->work);
>>       INIT_WORK(&ctx->put_work, fastrpc_context_put_wq);
>> @@ -1111,7 +1112,7 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
>>       int ret;
>>         cctx = fl->cctx;
>> -    msg->pid = fl->tgid;
>> +    msg->pid = fl->client_id;
>>       msg->tid = current->pid;
>>         if (kernel)
>> @@ -1294,7 +1295,7 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
>>           }
>>       }
>>   -    inbuf.pgid = fl->tgid;
>> +    inbuf.pgid = fl->client_id;
>>       inbuf.namelen = init.namelen;
>>       inbuf.pageslen = 0;
>>       fl->pd = USER_PD;
>> @@ -1396,7 +1397,7 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
>>           goto err;
>>       }
>>   -    inbuf.pgid = fl->tgid;
>> +    inbuf.pgid = fl->client_id;
>>       inbuf.namelen = strlen(current->comm) + 1;
>>       inbuf.filelen = init.filelen;
>>       inbuf.pageslen = 1;
>> @@ -1470,8 +1471,9 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
>>   }
>>     static struct fastrpc_session_ctx *fastrpc_session_alloc(
>> -                    struct fastrpc_channel_ctx *cctx)
>> +                    struct fastrpc_user *fl)
>>   {
>> +    struct fastrpc_channel_ctx *cctx = fl->cctx;
>>       struct fastrpc_session_ctx *session = NULL;
>>       unsigned long flags;
>>       int i;
>> @@ -1481,6 +1483,7 @@ static struct fastrpc_session_ctx *fastrpc_session_alloc(
>>           if (!cctx->session[i].used && cctx->session[i].valid) {
>>               cctx->session[i].used = true;
>>               session = &cctx->session[i];
>> +            fl->client_id = FASTRPC_CLIENTID_MASK | i;
>>               break;
>>           }
>>       }
>> @@ -1505,7 +1508,7 @@ static int fastrpc_release_current_dsp_process(struct fastrpc_user *fl)
>>       int tgid = 0;
>>       u32 sc;
>>   -    tgid = fl->tgid;
>> +    tgid = fl->client_id;
>>       args[0].ptr = (u64)(uintptr_t) &tgid;
>>       args[0].length = sizeof(tgid);
>>       args[0].fd = -1;
>> @@ -1580,11 +1583,10 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
>>       INIT_LIST_HEAD(&fl->maps);
>>       INIT_LIST_HEAD(&fl->mmaps);
>>       INIT_LIST_HEAD(&fl->user);
>> -    fl->tgid = current->tgid;
>>       fl->cctx = cctx;
>>       fl->is_secure_dev = fdevice->secure;
>>   -    fl->sctx = fastrpc_session_alloc(cctx);
>> +    fl->sctx = fastrpc_session_alloc(fl);
>>       if (!fl->sctx) {
>>           dev_err(&cctx->rpdev->dev, "No session available\n");
>>           mutex_destroy(&fl->mutex);
>> @@ -1648,7 +1650,7 @@ static int fastrpc_dmabuf_alloc(struct fastrpc_user *fl, char __user *argp)
>>   static int fastrpc_init_attach(struct fastrpc_user *fl, int pd)
>>   {
>>       struct fastrpc_invoke_args args[1];
>> -    int tgid = fl->tgid;
>> +    int tgid = fl->client_id;
>>       u32 sc;
>>         args[0].ptr = (u64)(uintptr_t) &tgid;
>> @@ -1804,7 +1806,7 @@ static int fastrpc_req_munmap_impl(struct fastrpc_user *fl, struct fastrpc_buf *
>>       int err;
>>       u32 sc;
>>   -    req_msg.pgid = fl->tgid;
>> +    req_msg.pgid = fl->client_id;
>>       req_msg.size = buf->size;
>>       req_msg.vaddr = buf->raddr;
>>   @@ -1890,7 +1892,7 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
>>           return err;
>>       }
>>   -    req_msg.pgid = fl->tgid;
>> +    req_msg.pgid = fl->client_id;
>>       req_msg.flags = req.flags;
>>       req_msg.vaddr = req.vaddrin;
>>       req_msg.num = sizeof(pages);
>> @@ -1980,7 +1982,7 @@ static int fastrpc_req_mem_unmap_impl(struct fastrpc_user *fl, struct fastrpc_me
>>           return -EINVAL;
>>       }
>>   -    req_msg.pgid = fl->tgid;
>> +    req_msg.pgid = fl->client_id;
>>       req_msg.len = map->len;
>>       req_msg.vaddrin = map->raddr;
>>       req_msg.fd = map->fd;
>> @@ -2033,7 +2035,7 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp)
>>           return err;
>>       }
>>   -    req_msg.pgid = fl->tgid;
>> +    req_msg.pgid = fl->client_id;
>>       req_msg.fd = req.fd;
>>       req_msg.offset = req.offset;
>>       req_msg.vaddrin = req.vaddrin;
>