From: James Bottomley <jejb@linux.vnet.ibm.com>
To: Colin King <colin.king@canonical.com>,
Hannes Reinecke <hare@suse.com>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
linux-scsi@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] scsi: aic7xxx: Fix unintended sign extension issue
Date: Thu, 25 Oct 2018 15:32:49 +0000 [thread overview]
Message-ID: <1540481569.3006.5.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <20181025151334.15622-1-colin.king@canonical.com>
On Thu, 2018-10-25 at 16:13 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> In the expression "ahc_inb(ahc, port+3) << 24", the initial value is
> a u8, but is promoted to a signed int, then sign-extended to
> uint64_t.
Why is this, that's highly non intuitive? The compiler is supposed to
promote to the biggest type, which is uint64_t and then do the
calculation
James
WARNING: multiple messages have this Message-ID (diff)
From: James Bottomley <jejb@linux.vnet.ibm.com>
To: Colin King <colin.king@canonical.com>,
Hannes Reinecke <hare@suse.com>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
linux-scsi@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] scsi: aic7xxx: Fix unintended sign extension issue
Date: Thu, 25 Oct 2018 16:32:49 +0100 [thread overview]
Message-ID: <1540481569.3006.5.camel@linux.vnet.ibm.com> (raw)
In-Reply-To: <20181025151334.15622-1-colin.king@canonical.com>
On Thu, 2018-10-25 at 16:13 +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> In the expression "ahc_inb(ahc, port+3) << 24", the initial value is
> a u8, but is promoted to a signed int, then sign-extended to
> uint64_t.
Why is this, that's highly non intuitive? The compiler is supposed to
promote to the biggest type, which is uint64_t and then do the
calculation
James
next prev parent reply other threads:[~2018-10-25 15:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-25 15:13 [PATCH] scsi: aic7xxx: Fix unintended sign extension issue Colin King
2018-10-25 15:13 ` Colin King
2018-10-25 15:32 ` Joe Perches
2018-10-25 15:32 ` Joe Perches
2018-10-25 15:32 ` James Bottomley [this message]
2018-10-25 15:32 ` James Bottomley
2018-10-25 15:54 ` David Laight
2018-10-25 15:54 ` David Laight
2019-10-14 12:56 ` [PATCH] scsi: aic7xxx: fix unintended sign extension on left shifts Colin King
2019-10-14 12:56 ` Colin King
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