From: P J P <ppandit@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Fam Zheng <fam@euphon.net>, Paolo Bonzini <pbonzini@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>,
Ren Ding <rding@gatech.edu>
Subject: Re: [PATCH 1/2] megasas: use unsigned type for reply_queue_head
Date: Wed, 13 May 2020 16:50:52 +0530 (IST) [thread overview]
Message-ID: <nycvar.YSQ.7.76.2005131647000.1451610@xnncv> (raw)
In-Reply-To: <CAFEAcA8Y67h_Kc=M2i5xGz-sQpJwZ++n8wB8szdv0ziViUfmqw@mail.gmail.com>
+-- On Tue, 12 May 2020, Peter Maydell wrote --+
| > + uint16_t reply_queue_head;
|
| Using a 16-bit type here means that code like this:
|
| s->reply_queue_head = ldl_le_pci_dma(pcid, s->producer_pa);
| s->reply_queue_head %= MEGASAS_MAX_FRAMES;
|
| suddenly does a truncation of the 32-bit loaded value before
| the modulus operation, which is a bit odd, though since
| MEGASAS_MAX_FRAMES happens to be a power of 2 the end
| result won't change.
Yes, 16-bit also for its range of value is limitted to MEGASAS_MAX_FRAMES=2048.
| It's also a bit weird to change reply_queue_head's type
| but not reply_queue_tail or reply_queue_len.
That's in the second patch.
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
8685 545E B54C 486B C6EB 271E E285 8B5A F050 DE8D
next prev parent reply other threads:[~2020-05-13 11:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-07 10:57 [PATCH 0/2] use unsigned type for MegasasState fields P J P
2020-05-07 10:57 ` [PATCH 1/2] megasas: use unsigned type for reply_queue_head P J P
2020-05-12 18:52 ` Peter Maydell
2020-05-13 11:20 ` P J P [this message]
2020-05-07 10:57 ` [PATCH 2/2] megasas: use unsigned type for positive numeric fields P J P
2020-05-12 18:53 ` Peter Maydell
2020-05-13 11:22 ` P J P
2020-05-12 12:21 ` [PATCH 0/2] use unsigned type for MegasasState fields P J P
2020-05-12 13:42 ` Philippe Mathieu-Daudé
2020-05-12 18:37 ` P J P
2020-05-12 19:08 ` Alexander Bulekov
2020-05-12 19:48 ` Alexander Bulekov
2020-05-12 20:59 ` Philippe Mathieu-Daudé
2020-05-12 21:00 ` Alexander Bulekov
2020-05-13 11:13 ` P J P
2020-05-13 13:49 ` P J P
2020-05-13 14:20 ` Alexander Bulekov
2020-05-13 14:53 ` P J P
2020-05-13 17:08 ` Ding, Ren
2020-05-13 19:34 ` P J P
2020-05-13 14:53 ` Alexander Bulekov
[not found] ` <BN6PR07MB341283EBBF78F86AAA995382CABE0@BN6PR07MB3412.namprd07.prod.outlook.com>
2020-05-12 20:54 ` 回复: " Philippe Mathieu-Daudé
2020-05-13 11:07 ` P J P
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