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rxrpc: Impose a maximum number of client calls

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Impose a maximum on the number of client rxrpc calls that are allowed
simultaneously.  This will be in lieu of a maximum number of client
connections as this is easier to administed as, unlike connections, calls
aren't reusable (to be changed in a subsequent patch)..

This doesn't affect the limits on service calls and connections.

Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells 2020-07-02 14:59:46 +01:00
parent 4349abdb40
commit b7a7d67408
3 changed files with 49 additions and 3 deletions
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7
net/rxrpc/af_rxrpc.c
View file

@ -308,9 +308,10 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
key = NULL; /* a no-security key */
memset(&p, 0, sizeof(p));
p.user_call_ID = user_call_ID;
p.tx_total_len = tx_total_len;
p.interruptibility = interruptibility;
p.user_call_ID = user_call_ID;
p.tx_total_len = tx_total_len;
p.interruptibility = interruptibility;
p.kernel = true;
memset(&cp, 0, sizeof(cp));
cp.local = rx->local;

2
net/rxrpc/ar-internal.h
View file

@ -493,6 +493,7 @@ enum rxrpc_call_flag {
RXRPC_CALL_RX_HEARD, /* The peer responded at least once to this call */
RXRPC_CALL_RX_UNDERRUN, /* Got data underrun */
RXRPC_CALL_DISCONNECTED, /* The call has been disconnected */
RXRPC_CALL_KERNEL, /* The call was made by the kernel */
};
/*
@ -727,6 +728,7 @@ struct rxrpc_call_params {
u32 normal; /* Max time since last call packet (msec) */
} timeouts;
u8 nr_timeouts; /* Number of timeouts specified */
bool kernel; /* T if kernel is making the call */
enum rxrpc_interruptibility interruptibility; /* How is interruptible is the call? */
};

43
net/rxrpc/call_object.c
View file

@ -41,6 +41,11 @@ const char *const rxrpc_call_completions[NR__RXRPC_CALL_COMPLETIONS] = {
struct kmem_cache *rxrpc_call_jar;
static struct semaphore rxrpc_call_limiter =
__SEMAPHORE_INITIALIZER(rxrpc_call_limiter, 1000);
static struct semaphore rxrpc_kernel_call_limiter =
__SEMAPHORE_INITIALIZER(rxrpc_kernel_call_limiter, 1000);
static void rxrpc_call_timer_expired(struct timer_list *t)
{
struct rxrpc_call *call = from_timer(call, t, timer);
@ -209,6 +214,34 @@ static void rxrpc_start_call_timer(struct rxrpc_call *call)
call->timer.expires = now;
}
/*
* Wait for a call slot to become available.
*/
static struct semaphore *rxrpc_get_call_slot(struct rxrpc_call_params *p, gfp_t gfp)
{
struct semaphore *limiter = &rxrpc_call_limiter;
if (p->kernel)
limiter = &rxrpc_kernel_call_limiter;
if (p->interruptibility == RXRPC_UNINTERRUPTIBLE) {
down(limiter);
return limiter;
}
return down_interruptible(limiter) < 0 ? NULL : limiter;
}
/*
* Release a call slot.
*/
static void rxrpc_put_call_slot(struct rxrpc_call *call)
{
struct semaphore *limiter = &rxrpc_call_limiter;
if (test_bit(RXRPC_CALL_KERNEL, &call->flags))
limiter = &rxrpc_kernel_call_limiter;
up(limiter);
}
/*
* Set up a call for the given parameters.
* - Called with the socket lock held, which it must release.
@ -225,15 +258,21 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
{
struct rxrpc_call *call, *xcall;
struct rxrpc_net *rxnet;
struct semaphore *limiter;
struct rb_node *parent, **pp;
const void *here = __builtin_return_address(0);
int ret;
_enter("%p,%lx", rx, p->user_call_ID);
limiter = rxrpc_get_call_slot(p, gfp);
if (!limiter)
return ERR_PTR(-ERESTARTSYS);
call = rxrpc_alloc_client_call(rx, srx, gfp, debug_id);
if (IS_ERR(call)) {
release_sock(&rx->sk);
up(limiter);
_leave(" = %ld", PTR_ERR(call));
return call;
}
@ -243,6 +282,8 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
trace_rxrpc_call(call->debug_id, rxrpc_call_new_client,
atomic_read(&call->usage),
here, (const void *)p->user_call_ID);
if (p->kernel)
__set_bit(RXRPC_CALL_KERNEL, &call->flags);
/* We need to protect a partially set up call against the user as we
* will be acting outside the socket lock.
@ -471,6 +512,8 @@ void rxrpc_release_call(struct rxrpc_sock *rx, struct rxrpc_call *call)
BUG();
spin_unlock_bh(&call->lock);
rxrpc_put_call_slot(call);
del_timer_sync(&call->timer);
/* Make sure we don't get any more notifications */