Drivers: hv: vmbus: finally fix hv_need_to_signal_on_read()

Commit a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in
hv_need_to_signal_on_read()")
added the proper mb(), but removed the test "prev_write_sz < pending_sz"
when making the signal decision.

As a result, the guest can signal the host unnecessarily,
and then the host can throttle the guest because the host
thinks the guest is buggy or malicious; finally the user
running stress test can perceive intermittent freeze of
the guest.

This patch brings back the test, and properly handles the
in-place consumption APIs used by NetVSC (see get_next_pkt_raw(),
put_pkt_raw() and commit_rd_index()).

Fixes: a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in
hv_need_to_signal_on_read()")

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reported-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Tested-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

path: root/include/crypto/ablk_helper.h

/*
 * Shared async block cipher helpers
 */

#ifndef _CRYPTO_ABLK_HELPER_H
#define _CRYPTO_ABLK_HELPER_H

#include <linux/crypto.h>
#include <linux/kernel.h>
#include <crypto/cryptd.h>

struct async_helper_ctx {
	struct cryptd_ablkcipher *cryptd_tfm;
};

extern int ablk_set_key(struct crypto_ablkcipher *tfm, const u8 *key,
			unsigned int key_len);

extern int __ablk_encrypt(struct ablkcipher_request *req);

extern int ablk_encrypt(struct ablkcipher_request *req);

extern int ablk_decrypt(struct ablkcipher_request *req);

extern void ablk_exit(struct crypto_tfm *tfm);

extern int ablk_init_common(struct crypto_tfm *tfm, const char *drv_name);

extern int ablk_init(struct crypto_tfm *tfm);

#endif /* _CRYPTO_ABLK_HELPER_H */