| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20130429141530.GA4789@ennui.austin.ibm.com>
Date: Mon, 29 Apr 2013 09:15:30 -0500
From: Kent Yoder <key@...ux.vnet.ibm.com>
To: Peter Hüwe <PeterHuewe@....de>
Cc: tpmdd-devel@...ts.sourceforge.net,
Mathias Leblanc <mathias.leblanc@...com>,
Rajiv Andrade <mail@...jiv.net>,
Marcel Selhorst <tpmdd@...horst.net>,
Sirrix AG <tpmdd@...rix.com>,
Jean-Luc Blanc <jean-luc.blanc@...com>,
linux-kernel@...r.kernel.org,
Matthias Leblanc <matthias.leblanc@...il.com>
Subject: Re: [tpmdd-devel] [PATCH 1/1] TPM: STMicroelectronics st33 driver SPI
On Sun, Apr 28, 2013 at 03:16:33AM +0200, Peter Hüwe wrote:
> Hi Matthias,
>
> it's nice to see that you consider most of the comments, unfortunately I still
> have some left ;)
>
> > +/*
> > + * tpm_st33_spi_init initialize driver
> > + * @return: 0 if successful, else non zero value.
> > + */
> > +static int __init tpm_st33_spi_init(void)
> > +{
> > + return spi_register_driver(&tpm_st33_spi_driver);
> > +}
> > +
> > +/*
> > + * tpm_st33_spi_exit The kernel calls this function during unloading the
> > + * module or during shut down process
> > + */
> > +static void __exit tpm_st33_spi_exit(void)
> > +{
> > + spi_unregister_driver(&tpm_st33_spi_driver);
> > +}
> > +
> > +module_init(tpm_st33_spi_init);
> > +module_exit(tpm_st33_spi_exit);
>
> Please use module_spi_driver(&tpm_st33_spi_driver); instead
> Boilerplate code sucks.
>
>
> > + u8 *data_buffer = platform_data->tpm_spi_buffer[0];
> > + struct spi_transfer xfer = {
> > + .tx_buf = data_buffer,
> > + .rx_buf = platform_data->tpm_spi_buffer[1],
> > + };
> > + struct spi_message msg;
> >...
> > + xfer.len = total_length;
> > + spi_message_init(&msg);
> > + spi_message_add_tail(&xfer, &msg);
> > + value = spi_sync(dev, &msg);
>
>
> Doesn't spi_write fit here ?
>
> static inline int
> spi_write(struct spi_device *spi, const void *buf, size_t len)
> {
> struct spi_transfer t = {
> .tx_buf = buf,
> .len = len,
> };
> struct spi_message m;
>
> spi_message_init(&m);
> spi_message_add_tail(&t, &m);
> return spi_sync(spi, &m);
> }
>
> Seems pretty identical.
> -> This would save some lines of code,
> and again - boilerplate code sucks.
> Same applies to spi_read,
>
>
>
> The driver generates some gcc warnings:
> drivers/char/tpm/tpm_spi_stm_st33.c: In function 'read8_reg':
> drivers/char/tpm/tpm_spi_stm_st33.c:180:5: warning: unused variable 'latency'
> [-Wunused-variable]
> drivers/char/tpm/tpm_spi_stm_st33.c: In function 'tpm_stm_spi_status':
> drivers/char/tpm/tpm_spi_stm_st33.c:353:2: warning: 'data' is used
> uninitialized in this function [-Wuninitialized]
> drivers/char/tpm/tpm_spi_stm_st33.c: In function 'get_burstcount':
> drivers/char/tpm/tpm_spi_stm_st33.c:450:12: warning: 'temp' is used
> uninitialized in this function [-Wuninitialized]
> drivers/char/tpm/tpm_spi_stm_st33.c: In function 'check_locality':
> drivers/char/tpm/tpm_spi_stm_st33.c:369:22: warning: 'data' may be used
> uninitialized in this function [-Wuninitialized]
Thanks for pointing this out Peter -- it made me realize my bash
aliases for checking were not working. :-)
Please take a look at these too:
drivers/char/tpm/tpm_spi_stm_st33.c:446 get_burstcount() warn: unsigned
'status' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:452 get_burstcount() warn: unsigned
'status' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:523 recv_data() warn: unsigned
'status' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:572 tpm_stm_spi_send() warn:
unsigned 'ret' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:590 tpm_stm_spi_send() warn:
unsigned 'ret' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:613 tpm_stm_spi_send() warn:
unsigned 'ret' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:836 tpm_st33_spi_probe() warn:
unsigned 'err' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:842 tpm_st33_spi_probe() warn:
unsigned 'err' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:854 tpm_st33_spi_probe() warn:
unsigned 'err' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:859 tpm_st33_spi_probe() warn:
unsigned 'err' is never less than zero.
drivers/char/tpm/tpm_spi_stm_st33.c:863 tpm_st33_spi_probe() warn:
unsigned 'err' is never less than zero.
Kent
>
>
> The driver does give me some smatch errors:
>
> $ LANG=C make -j16 C=1 CHECK=smatch
> CHECK drivers/char/tpm/tpm_spi_stm_st33.c
> drivers/char/tpm/tpm_spi_stm_st33.c:882 tpm_st33_spi_probe() warn: variable
> dereferenced before check 'platform_data' (see line 781)
> drivers/char/tpm/tpm_spi_stm_st33.c:980 tpm_st33_spi_pm_resume() warn: should
> this be a bitwise op?
> drivers/char/tpm/tpm_spi_stm_st33.c:980 tpm_st33_spi_pm_resume() warn: should
> this be a bitwise op?
>
>
>
> and some sparse errors:
> drivers/char/tpm/tpm_spi_stm_st33.c:102:35: warning: cast removes address
> space of expression
> drivers/char/tpm/tpm_spi_stm_st33.c:171:35: warning: cast removes address
> space of expression
> drivers/char/tpm/tpm_spi_stm_st33.c:299:19: warning: cast removes address
> space of expression
> drivers/char/tpm/tpm_spi_stm_st33.c:311:15: warning: symbol
> 'wait_for_serirq_timeout' was not declared. Should it be static?
> drivers/char/tpm/tpm_spi_stm_st33.c:546:19: warning: cast removes address
> space of expression
>
>
>
>
>
> And here are some other, rather subjective remarks:
>
> > + for (; nbr_dummy_bytes < total_length &&
> > + ((u8 *)xfer.rx_buf)[nbr_dummy_bytes] == 0;
> > + nbr_dummy_bytes++)
> > + ;
>
> Not sure if it would be easier to read using a while and putting the increment
> into the loop body
>
> >+ while (nbr_dummy_bytes < total_length &&
> >+ ((u8 *)xfer.rx_buf)[nbr_dummy_bytes] == 0)
> >+ nbr_dummy_bytes++;
>
> I usually don't like empty loop bodies, as they tend to be overlooked.
>
>
>
> > +static u32 SPI_WRITE_DATA(struct tpm_chip *tpm, u8 tpm_register,
> > + u8 *tpm_data, u16 tpm_size)
> > +{
> > + u8 value = 0;
> > + value = write8_reg(tpm, tpm_register, tpm_data, tpm_size);
> > +
> > + switch (value) {
> > + case TPM_ST_SPI_OK:
> > + return TPM_ST_SPI_OK;
> > + case 0:
> > + return 0;
> > + default:
> > + return -EBUSY;
> > + }
> > +} /* SPI_WRITE_DATA() */
>
> Why do you need a wrapper function here for the return code?
> write8_reg is only called from this location, so why doesn't it return the
> correct error code directly?
> *confused*
>
>
> Same applies to read8_reg.
>
>
>
>
> > +static int _wait_for_interrupt_serirq_timeout(struct tpm_chip *chip,
> > + unsigned long timeout)
> Is only called from wait_for_serirq_timeout - I'm not really sure if it helps
> readability to have a separate function.
>
>
>
>
> > + .resume = tpm_st33_spi_pm_resume,
> > + .suspend = tpm_st33_spi_pm_suspend,
> Maybe use
> SIMPLE_DEV_PM_OPS
> instead as it is (afaik) the new standard way for PM_OPS.
> The conversion should be pretty similar to the one in your I2C TPM driver:
> https://github.com/shpedoikal/linux/commit/d459335381eca1cb91fefb87021d3d172342e55a
>
>
> Regards,
> Peter
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists