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path: root/arch/um/drivers/vhost_user.h
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2020-06-02um: virtio: Replace zero-length array with flexible-arrayGustavo A. R. Silva
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Richard Weinberger <richard@nod.at>
2020-03-29um: virtio: Implement VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONSJohannes Berg
Implement in-band notifications that are necessary for running vhost-user devices under externally synchronized time-travel mode (which is in a follow-up patch). This feature makes what usually should be eventfd notifications in-band messages. We'll prefer this feature, under the assumption that only a few (simulation) devices will ever support it, since it's not very efficient. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15um: virtio: Implement VHOST_USER_PROTOCOL_F_REPLY_ACKJohannes Berg
Implement the VHOST_USER_PROTOCOL_F_REPLY_ACK extension for both slave requests (previous patch) where we have to reply and our own requests where it helps understand if the slave failed. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15um: virtio: Implement VHOST_USER_PROTOCOL_F_SLAVE_REQJohannes Berg
Implement the communication channel for the device to notify us of some events, and notably implement the handling of the config updates needed for the combination of this feature and VHOST_USER_PROTOCOL_F_CONFIG. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15um: drivers: Add virtio vhost-user driverErel Geron
This module allows virtio devices to be used over a vhost-user socket. Signed-off-by: Erel Geron <erelx.geron@intel.com> Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: Richard Weinberger <richard@nod.at>