Re: [06/10,V2] spi: Add SPI driver for mx233/mx28

Hi Marek,

On Wed, Aug 01, 2012 at 04:31:04AM +0200, Marek Vasut wrote:

Dear Guenter Roeck,

[...]

quoted

quoted

+static int __devexit mxs_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *host;
+	struct mxs_spi *spi;
+	struct mxs_ssp *ssp;
+
+	host = platform_get_drvdata(pdev);
+	spi = spi_master_get_devdata(host);
+	ssp = &spi->ssp;
+
+	spi_unregister_master(host);
+
+	platform_set_drvdata(pdev, NULL);
+
+	clk_disable_unprepare(ssp->clk);
+
+	spi_master_put(host);
+	kfree(host);
+

Is the kfree() here and in the probe function really necessary ?

It certainly would seem that way.

quoted

Couple of reasons for asking: No other SPI master driver calls it in the
remove function (unless I missed it), most drivers don't call it in the
probe function error path, and if I call it in the remove function in a
SPI master driver I am working on, and load/unload the module several
times in a row, I get a nasty kernel crash.

It seems the spi_master class takes care of that kfree() in 
spi.c:spi_master_release() . Good catch, thanks!

Given that, and assuming that spi_master_put() results in the call to
spi_master_release() for both the error case in the probe function and for
the release function, I take it that the kfree() is not needed at all,
and that the documentation for spi_alloc_master() is wrong. Does that sound
reasonable ?

Thanks,
Guenter

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