mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish

[ This is old but the inconsistent NULL check was added so deliberately
that it looks odd so I'm sending the email. -dan ]

Hello Ben Dooks,

This is a semi-automatic email about new static checker warnings.

The patch b7b4d3426d2b: "mmc: sdhci: Check mrq->cmd in sdhci_tasklet_finish" from Apr 27, 2011, leads to the following Smatch complaint:

drivers/mmc/host/sdhci.c:2151 sdhci_tasklet_finish()

	 error: we previously assumed 'mrq->cmd' could be null (see line 2124)

drivers/mmc/host/sdhci.c
2123 if (!(host->flags & SDHCI_DEVICE_DEAD) &&
2124 ((mrq->cmd && mrq->cmd->error) ||

                      ^^^^^^^^

Patch adds NULL check.

2125 (mrq->data && (mrq->data->error ||
2126 (mrq->data->stop && mrq->data->stop->error))) ||
2127 (host->quirks & SDHCI_QUIRK_RESET_AFTER_REQUEST))) {
2128
2129 /* Some controllers need this kick or reset won't work here */
2130 if (host->quirks & SDHCI_QUIRK_CLOCK_BEFORE_RESET)
2131 /* This is to force an update */
2132 host->ops->set_clock(host, host->clock);
2133
2134 /* Spec says we should do both at the same time, but Ricoh
2135 controllers do not like that. */
2136 sdhci_do_reset(host, SDHCI_RESET_CMD);
2137 sdhci_do_reset(host, SDHCI_RESET_DATA);
2138 }
2139
2140 host->mrq = NULL;
2141 host->cmd = NULL;
2142 host->data = NULL;
2143
2144 #ifndef SDHCI_USE_LEDS_CLASS
2145 sdhci_deactivate_led(host);
2146 #endif
2147
2148 mmiowb();
2149 spin_unlock_irqrestore(&host->lock, flags);
2150

  2151		mmc_request_done(host->mmc, mrq);
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

But we "mrq->cmd" is not checked here and it's dereferenced inside the mmc_request_done() function call.

  2152		sdhci_runtime_pm_put(host);
  2153	}

regards,
dan carpenter