From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Hutterer Subject: [PATCH] Input: update documentation for EVIOCGMASK/EVIOCSMASK Date: Thu, 21 Apr 2016 13:18:26 +1000 Message-ID: <20160421031826.GA6719@jelly.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from leo.clearchain.com ([199.73.29.74]:32157 "EHLO mail.clearchain.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751707AbcDUDSd (ORCPT ); Wed, 20 Apr 2016 23:18:33 -0400 Content-Disposition: inline Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: linux-input@vger.kernel.org Cc: Dmitry Torokhov , David Herrmann , Benjamin Tissoires The current implementation does not match the most intuitive reading of the documentation. The documentation suggests that anything after FOO_CNT would be reset to zeroes. The implementation however works on long boundaries instead. For example, a client requesting the EV_REL mask will see the first 64 bits set to one in the default mask, everything else is zero. Setting a mask will apply the mask for the first 64 bits, the others are cleared. There are few use-cases where this actually matters to a client - if a device doesn't have the event code anyway the mask doesn't matter. So change two absolute statements to a "may" to indicate that bits may or may not be set. Signed-off-by: Peter Hutterer --- include/uapi/linux/input.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/input.h b/include/uapi/linux/input.h index 0111384..6069524 100644 --- a/include/uapi/linux/input.h +++ b/include/uapi/linux/input.h @@ -181,7 +181,7 @@ struct input_mask { * The default event mask for a client has all bits set, i.e. all events * are forwarded to the client. If the kernel is queried for an unknown * event type or if the receive buffer is larger than the number of - * event codes known to the kernel, the kernel returns all zeroes for those + * event codes known to the kernel, the kernel may return zeroes for those * codes. * * At maximum, codes_size bytes are copied. @@ -204,7 +204,7 @@ struct input_mask { * is unknown to the kernel, or if the number of event codes specified in * the mask is bigger than what is known to the kernel, the ioctl is still * accepted and applied. However, any unknown codes are left untouched and - * stay cleared. That means, the kernel always filters unknown codes + * may be cleared. That means, the kernel always filters unknown codes * regardless of what the client requests. If the new mask doesn't cover * all known event-codes, all remaining codes are automatically cleared and * thus filtered. -- 2.7.3